All language subtitles for how.it.works.s01e01.metal.1080p.hdtv

This is the vibrant heart
of a 21st century city.

There's something strange but
wonderful about Piccadilly Circus.

Strange because,
as far as the eye can see,

there's nothing natural.

There's not a tree, not a flower,
not a blade of grass.

But wonderful because we made it.

We've transformed matter
to create the world that we live in.

My name is Mark Miodownik,
and as a materials scientist

I've spent my life
trying to understand

what's hidden
deep beneath the surface

of everything
that makes up our modern world.

For me, the story of how materials
have driven human civilisation

from the Stone Age
to the Silicon Age

is the most exciting story
in science.

Without our mastery of the stuff
that we found around us,

we would have no buildings, no cars,

no roads, no art.

Nothing.

This series is the story of how
we created our 21st century world,

how we unlocked the secrets
of the raw materials of our planet

and created our future.

Gleaming, lustrous, volatile metals.

Everything around us
is shaped by metal.

Metal has driven human civilisation
- power, war, industry -

and yet it's mysterious stuff.

It's only in the last 60 years
that we've begun to unravel

the secrets hidden deep within
the metal at the atomic scale,

how it is that it can be
strong enough to build empires

and yet soft enough
that 1 can crumple it in my hand,

why it is
that it seems inert and unchanging

and yet sometimes can behave
almost as if it's alive.

Take a look at this.
It looks like a normal paperclip,

but if I scrunch it up
so it's unrecognisable

and then put a blowtorch on it...

HE LAUGHS

Isn't that amazing?
Isn't that marvellous?

1 mean, that is indistinguishable
from magic.

This...
This metal remembers its shape.

Normal metals don't do this.

We've engineered this metal
to have a memory.

How we got from the Stone Age
to being able to manipulate matter

and make metals like this
is the story of this programme.

Let me take you back
to when it all began -

the dawn of civilisation.

This is where our ancestors
first settled.

It's where East meets West,
where Africa meets Asia.

Underneath my feet,
the Earth's crust is shifting.

And the geology here
gave our ancestors

access to something
that would change their world.

This is one of
the first places on Earth

that man stepped out
of the Stone Age

and transformed rock into metal.

And it all started with copper.

It's these green streaks
that may have been the first clue

there was something
a bit special about this rock.

Somehow, we worked out that
when you've got this type of rock,

you can do something amazing
with it.

We don't really know
when our ancestors first discovered

what this marvellous
green rock can do.

They might have just ground it up

to use it as a powder
to decorate their pottery,

or maybe it happened to be
just lying by the fire.

But either way, they discovered
something really rather marvellous

about what this stuff can do
if you add it to a fire.

Now, the thing about the fire is,
you need it to be very, very hot

and for that you need a lot of air,

and that's why they built
their fires on hillsides.

These hillsides are extremely windy,

so the air is being funnelled
into the fire.

It's actually a genius idea.

And then,
when they'd got a very hot fire,

they added the green rock.

And then they kept the temperature
high for hours, and they waited.

So when the fire died down,

they would have found bits
of a hard stone, black stone,

but amongst that black stone,

look, there's tiny little
shiny bits of metal.

They'd transformed rock into metal,
it's absolutely extraordinary!

Here we have rock...
1 mean, there's rock everywhere,

but they'd found
the power of transformation.

Look! Look how bright that is!
A bright piece of copper.

We know they did it on this hillside
because we've found the remnants

from early smelting
of our ancestors.

So they did that here,

and this was the beginning
of human civilisation,

the age of metals.

Our ancestors realised that
with copper,

they could make strong tools,

better than anything
they'd had before.

This copper chisel represents
the leap out of the Stone Age.

Everything we have
in our civilisation today

is due to metal tools like this.

If they get blunt,
we can sharpen them.

If they get bent,
we can re-straighten them.

If they get damaged,
we can repair them.

It's simply
the perfect material for tools.

Nothing else
our ancestors had in their world

could have done this -
not stone, not bone, not wood.

So what's so special about metal?

It's all down
to its inner structure.

Metals are made of crystals,
and that's a very surprising fact,

because they don't seem to behave

anything like the crystals
we are more familiar with.

I'll show you what I mean.
I've got a quartz crystal here.

That's what you mean
when you say "crystal".

And this is what a quartz crystal
says when you hit it with a hammer.

You see? That's what we think of

when we think of crystals being hit
with a hammer.

But if 1 say 10 you that this piece
of metal is made of crystals,

you know already
that it's not going to do that.

It's going to be quite malleable,
I can do this.

In fact, that's how you work metal,
you change its shape.

And that's...that's really strange,
because that means

that the crystals in this metal are
changing shape instead of exploding.

Inside the metal crystal,

the basic building blocks of
everything in the universe, atoms,

are arranged
in a regular lattice structure.

But they're not static.

When they're hit, metals can shuffle
atoms from one side to the other,

like a Mexican wave.

They can move, rearrange themselves,

and this is why
the crystal can change shape.

Metals alone behave like this.

As well as not shattering
when you hit them,

they actually get stronger.

The impact creates waves
of shuffling atoms

which collide with each other
and create blockages.

These make it harder
for the atoms to shuffle around,

making the metal stronger.

So the more hammering you do,

the more blockages you form
in the crystal,

and so the stronger the metal gets.

It was the strength of metal
over stone and wood

that became its main attraction.

With metal tools,

our ancestors could conceive
of grandiose projects.

It's believed the limestone blocks
that built the pyramids of Egypt

were carved using copper chisels.

But soon copper wasn't enough.

Our love affair with metals
consumed us.

Here on the shores
of what's now Israel,

metals from distant lands
were traded.

And it was one of these, tin,
that moved on the story of metals,

as our ancestors
began to mix metals together.

So they took some copper...some tin,

and they melted them together
to make a mixture,

which we call an alloy.

And they created a new metal,
bronze.

Bronze was the creation
of man the metal-smith,

rather than a gift of nature,

and it gave its name to a new era,
the Bronze Age.

Now, this is a nail
made out of pure copper,

and as metals go,
copper's pretty weak.

Have a look at this.

After a while,
it just can't get any further,

and so the metal itself buckles.

If I do the same with tin nail...
let's see what happens.

Tin is actually softer
than copper, even.

That's a real joke for a nail,
isn't it?

But here's the odd thing.

The mixture, a bronze nail...

well, this is much stronger.

Ha-ha-ha-ha!

It's so strong it's knocking
the wood out of this vice.

So that's odd, isn't it?
You add two soft metals together,

and you get something much harder
and much stronger.

How do you explain that?

In bronze, the tin atoms
replace some of the copper atoms,

which are smaller.

This interferes
with the lattice structure,

making it more difficult for the
atoms to shuffle across the crystal.

This makes the new alloy
much stronger.

The strength of bronze

gave us the means not only to build,
but to destroy.

As well as tools,

we made the swords and shields
of conquest and dominion.

Bronze propelled the evolution

of a new, complex,
more technological society.

It also created new occupations,

such as mining, manufacturing
and trading metals.

Bronze dominated the world
for 2,000 years.

But it wasn't the metal
to take us into the industrial age.

About 1200 BC,
another metal rose to prominence.

Iron.

Iron is one of the most plentiful
elements in the Earth's crust,

but it's fiendishly difficult
to work with.

Owen Bush has spent nearly 20 years
learning how to tame iron.

It doesn't look very promising

as a way to start a civilisation,
does it?

It's the basics, the beginning of it.
So what happens next?

You take this stuff... Heat it up.
OK. And hit it.

Pure iron can't be easily extracted
from its native rock.

There are several stages before
it can be hammered into submission.

So this whole process of bashing it

and putting it back in the furnace
is to get purer and purer iron.

Yes, it is. You're trying to purify

this very strange substance
that's come out of the furnace.

Yeah, I'm literally
beating the crap out of it.

As Owen continues
to hammer the iron,

more and more impurities are exposed
to the air and burn off as sparks.

By bashing it,
you're left with a purer metal.

This is wrought iron,

wrought at the blacksmith's anvil.

If you'd like to have a bash,
by all means.

I would love to do that,
I've never done that before.

Mastery of iron by our ancestors
would not have been easy.

To show me just how difficult it is
to work with, Owen challenges me

to make the simplest and most common
of iron products.

Well, we're going to try and squash
it flat and forge a nail out of it.

1 know in theory
what this stuff should do,

but I've never hit it with a hammer,
I've never done what you do.

That's good to go. OK.

Right.

That's it. Oh, yeah, so there's bits
flying off, 1 can really feel...

You can feel something happening
in the metal.

There's a kind of response to you.

There's something addictive to this.
Yeah, it's primal, isn't it? Yeah!

Now, yeah, back in. Back in, yeah.

You can see, when it came out,
it was bubbling,

and as it cools down the...

Yeah, then 1 can see it
becoming a bit brittle.

It sort of freezes in your hands
and you're not making any headway.

Yeah, well,
you're getting feedback from it,

and because every bit's different,
you have to use that feedback

so you don't end up with a flattened,
destroyed blob, fundamentally.

What I began to learn with Owen

is just how much of this process
is trial and error,

how different iron ores
could behave very differently.

All the variables
of heat, of ore, of fuel

meant that the quality of your iron

depended absolutely
on the quality of your blacksmith.

You're just hammering down to give
it a bit of a head.

Lovely.

That's quite satisfying.

You got some good hits in there.

There we have our little nail.

What a beauty! My first nail.

And it was the iron nail

that was to underpin
the next great civilisation.

The Romans were expert
at manipulating iron.

Their blacksmiths traveled
everywhere with them,

forging the weapons
and shields of Empire.

But the Romans never
built big with iron.

They were limited by what the
blacksmith could do at his anvil.

And so, we would be constrained
for another 1,500 years

until the next great step
in our mastery of metals -

a new technology that would unleash
the Industrial Revolution.

Ironbridge Gorge in Shropshire was
at the heart of this new revolution.

A man called Abraham Darby
started making iron pots

and, almost overnight,

he turned this sleepy valley
into the iron capital of England.

The key was the fuel.

Darby realised that,
with fires made from coke,

partially burned coal, he could
reach much higher temperatures.

And that would do something
that would transform iron.

When it got hot enough,
something happened

that opened up
vast new possibilities for iron.

It melted and became liquid.

This was the birth of a new
type of iron - cast iron.

18th century engineers
must barely have been able

to contain their excitement.

Now, instead of working
iron at an anvil,

they could pour it into a mould.

And the mould could be
any shape or size they wanted.

Darby's furnaces
worked around the clock.

They turned the night sky red.

And the roar could be
heard for miles around.

There seemed no limit to what this
exuberant new industry could do.

And this was proof of it. It was
built by Abraham Darby's grandson.

And it was the first iron
bridge in the world.

This was a golden
age of engineering,

when it seemed only our imaginations
could limit us.

We crossed whole countries
with iron railways.

We crossed rivers with iron bridges.

TRAIN WHISTLE SOUNDS

The engineers of
the industrial world

were seduced into thinking that
their every ambition was achievable.

But, the dreams were
about to come crashing down.

On 1st June, 1878, the great
and the good of Victorian Britain

were assembled by the banks
of the River Tay here in Dundee

to applaud the opening of
the longest bridge in the world.

It had been
designed by Thomas Bouch,

an ambitious railway engineer,
who may have considered

the Tay Bridge a stepping stone
to a knighthood.

But, one dark winter's night
in 1879 would change all that.

A train left Edinburgh, north,
on the Aberdeen line.

Storms were raging
across the country.

And when the train got to the Tay,

gale force winds were
ripping through here.

As the train crossed the bridge,
something terrible happened.

The iron girders cracked,
and the bridge collapsed.

The train plunged
into the icy waters.

There were no survivors.

It was a terrible human tragedy.

But what made it worse was that
it was a man-made tragedy.

The pinnacle of our engineering
achievement,

the iron bridge, had failed.

Nobody had any idea why.

It was a Victorian mystery.

1 asked Rhona Rogers, from Dundee
Museum, how events unfolded that night.

A couple of hours after the train
had plunged into the water,

crowds began to gather on
the north side of the bridge.

People looking for loved ones
that were expected home

waited for news with none coming.

Tell me about Thomas Bouch,
how did he react?

He was on the boat the next day
that went out

to look for survivors
or any signs of the wreckage,

and he was described as being
in a very sorry state.

And he rapidly became very ill and
then died a couple of months later.

He died from water on the lung,
that's the official cause of death,

but a lot of people say it was
shame and stress,

the shame and stress of what had
happened, about his loss of career

and not becoming the success in life
he had wanted.

How did the rest of the country
react?

Was it just a local tragedy?

No, it was the longest bridge of
its type at this time in the world,

so reactions were global.

It affected engineering
on a world scale.

And it was a very personal
thing for people in Dundee.

Quite significant, isn't it, that you can
still see the remnants of the bridge now?

They're like tombstones,
aren't they?

Yes, a permanent memorial
to the dead, yes,

the 75 who lost their lives,
of which only 45 were washed ashore.

The cornerstone of the
Industrial Revolution - cast iron -

had failed catastrophically.

Now the burning question was, why?

In the immediate aftermath
of the disaster,

there were many theories
as to what had gone wrong.

I've come to Sheffield University
to test my own theory.

Postgraduate students Ben Thomas
and Lucy Johnson have designed

and built a scale model of one
of the bridge's iron pillars,

and we're going to put it
to the test.

So, just like in the real structure, you had
these cast irons and this cross brace stuff

is exactly how the piers of this
railway bridge were constructed? Yeah.

'The corners of each pier of the
bridge were made of cast iron,

'and that's what
we're testing today.

'The first test is to see how good the pillar
is at carrying loads under compression.'

'Could the cast iron have collapsed
just under the weight of the train?

Cast iron's supposed to be quite
strong in compression,

so we've got a very simple compression
test straight through the middle here.

'We started to apply
pressure to the model.

'But before the pillar gave way,
this happened..

LOUD METALLIC CLANG

Oh dear, what was that?
What happened there?

There's no obvious breaks,
which is good news.

It may be that it started to crack
up here on the test rig.

Really?

So we might have broken the test
rig... No, don't say that!

Lucy, give me hope.

We can't see that anything's obviously
broken with the bridge itself. OK.

So, the good news is that the bridge
is stronger than our test rig?

It looks that way, yeah.

'Cast iron is known to be strong
under compression,

'and the bridge had taken the weight
of the train many times before.

'But there were other forces at play
on the bridge that night,

'not least the strong winds.'

So, because of the wind, the gale
force winds, there were forces

on these cast iron struts that
would be making them bend that way.

They were all trying to bend
over like a tree in the wind,

and the question is, can that
material take that kind of force?

'In that situation, one side
of the bridge will be compressed,

'but the other side will stretch.

'So 1 took a single bar
from the model

"and this time 1 put it in a machine
hat tests the metal under tension.

'I'm going to see what happens
when you stretch it.'

BANG

'With very little force, it snaps.'

'At the point where the bar broke is
evidence of what makes cast-iron weak.'

Look at where it's fractured.
There's this enormous hole there.

That is an impurity in the material
which has very little strength,

and when you use a microscope
to look at this material

you see not only big flaws in it,
like these strange holes,

but deep inside the metal there
are loads of little black blobs,

black-grey blobs, and they are
a material called graphite.

They're embedded in the material,
and there's no way to remove them,

you can make them smaller but they
are always going to be in cast iron.

It's the very process of making
cast iron that causes its weakness.

The casting process
traps in many of the impurities

that a blacksmith
would have hammered out.

The most important one is
graphite - carbon.

It forms lumps that sit within
the microstructure of the metal.

And it's these lumps
that make the metal weak.

This is what graphite looks like.

You know it, because
it's the stuff of your pencil.

It's a very weak material,

so if you have loads of this stuff
embedded in your iron,

it's not surprising that
that iron is going to be weak.

But back in the 19th century,
this interior world of metals

was still hidden from us.

What it comes down to is this -
we were building bridges out of iron

without fully
understanding the material.

We needed to change our relationship
with metal

from one of mastery
to one of understanding.

All we really knew was that
cast iron had failed us.

We desperately needed
a stronger metal.

But the answer wouldn't lie in
making the purist iron possible.

It would turn out to be far
more complex.

The Victorian engineers looked to history
for the strongest iron they could find.

The metal smiths of old used it to
make swords of legendary strength.

They called it 'good iron'.

We call it steel.

Back in the forge, Owen is going to
reveal the secret of good iron -

making the iron pure,
but not too pure.

Following the techniques
of ancient swordsmiths,

he hammers the iron and then folds,
and heats and folds again,

exposing more and more of the iron to
the air, so the impurities burn away.

So I'm just going to
cut it in half...

Then bend it back on itself.

Back in the fire.

We had four layers,
now we've got eight, next fold 16.

If this was to be the edge material
of the blade I'd probably

take it up to somewhere between 700
and couple of thousand layers.

A thousand layers?

So what's coming off the edge there?
That's iron oxide.

So that's its skin, really? Yeah.

'Through a combination of skill
and experience the swordsmiths knew

'when their metal was pure enough
to hammer into a blade.

'Then they added at touch of magic
- it's called quenching.

'They thrust the red hot
blade into a cooling liquid.

"When they drew it out again
the edge had hardened!

When you read the accounts
written down about this process,

you find all sorts
of weird materials,

like, people would get the urine
of a redheaded boy,

or they'd get a goat which had
only fed on the fern for three days

and they would quench into that -
what do you think about this?

If it worked, if your master smith taught you
to quench in the urine of a redheaded boy,

then if it worked for him there's
no reason why you'd stop.

And, also it adds mystique,
doesn't it?

'Technique and temperature
worked a mysterious alchemy,

'creating a metal
that kept its sharp edge.

"A metal with almost magical
properties.

The master swordsmiths
had manipulated iron so skilfully

they had unwittingly
created a totally new metal.

Steel.

The strong, reliable metal
the Victorian engineers needed

to fulfil their growing ambitions.

But the problem is,
as we've just seen,

it takes a huge amount of time,
effort, expertise,

to just make this one, small blade.

So, if the Victorians
were going to use steel,

they were going to have to learn
how to mass-produce it.

And in order to do that they would have to
find out what was going on inside this metal.

A clue would come from another
feature of the swordsmith's art.

The pattern of the sword was
the must-have mark of quality.

Dipping the swords in acid made
the intricate swirling patterns,

created by the folding, twisting and
hammering, become more pronounced.

This process was called etching.

And etching would be the key
to revealing the secret of steel,

exactly what it was made of.

Here in Sheffield, in 1863,
the single-minded dedication

of one man provided the flash
of insight that changed everything.

Henry Clifton Sorby was perhaps
the last great scientific amateur

in an age when science was becoming
the concern of professionals.

Sorby pretty much invented the idea of
looking at metals through microscopes.

He was ridiculed by his colleagues.

But he persevered,
and it's lucky for as he did.

Here, I'm proud to say,
I have in front of me

the original samples he first made.

Sorby prepared his steel
samples in exactly the same way

as the ancient sword Smiths -
he etched them.

And when he looked at the intricate
patterns under the microscope,

Sorby discovered
the secret of steel's strength.

This is a 150-year-old
sample that he prepared.

Let me show you what he saw
and no-one else had ever seen.

The microscope revealed that steel was a very
pure form of iron, much purer than cast-iron.

But there's still a small
amount of impurity there.

The dark bits that look like rivers
are crystals that contain carbon.

It turned out the whole premise
of the iron industry had been false.

Everyone had thought that what you had
to do was beat out the impurities -

the purer the iron you could get
the better it would be -

And they were wrong.

Instead, what was needed was precisely
the right amount of impurity.

An alloy of iron and carbon
in exactly the right proportions.

This is the crystal
lattice of pure iron.

And this is steel.

Carbon atoms sit in the gaps
between the iron atoms,

making steel much stronger.

But you have to have just
the right amount of carbon.

In cast iron,
there's too much carbon

and the spare carbon atoms form
larger blobs within the crystal

and make the metal weaker.

Now we knew what made steel
so strong.

But we were still in the dark
about how to produce it cheaply

and on the industrial scale
that the 19th-century demanded.

One day, a Sheffield-based engineer
called Henry Bessemer

stood up at a British science
meeting and shocked his audience

by announcing he could
mass-produce steel.

It required no hammering,
no beating, no folding.

He could make tonnes of the stuff
in this, his Bessemer converter.

This huge bucket that Bessemer
designed would have contained

an enormous amount of molten iron,

and that, of course,
was full of carbon.

So what Bessemer suggested was that you made
this pipe that goes down the bottom here,

and they pumped air
through the liquid iron,

and that air contained oxygen,
and the oxygen reacted

with the carbon to create
carbon dioxide.

And Bessemer's idea was to just
do that long enough to get

the carbon content of the iron
down to about 1%.

And he designed these enormous
cranks on the side here,

so when the carbon content
of the steel is exactly right

you just crank the whole bucket
over and out pours masses

and masses of this
beautiful, liquid steel.

'I'm going to make steel in a way
that's based on Bessemer's principle.

'"Molten iron, which is full of impurities
like carbon, is poured into a bucket.

"1 blow oxygen through it,

'just as air was blown
through Bessemer's converter.

'The oxygen reacts with a carbon
to form carbon dioxide,

'removing most of the carbon.

'So you should be left with just the
right amount of carbon to make steel.'

Well, the process may be simple,
but it's insane.

I mean you are pumping oxygen
or air through a liquid metal,

and it gets white hot
and it's bubbling and you think,

this is fine,
making a small cauldron of it,

but imagine making a bucket load
of the stuff the size of this room!

That's what Bessemer was doing,
and having a go at it

1 realise quite
how avant-garde he was.

What he was proposing was
really extraordinary.

But the process had a major
disadvantage - it just didn't work.

It was too difficult
to hit precisely

the right amount of carbon -
just under 1%.

Bessemer and his converter
faced financial ruin.

But not for long.

British metallurgist Robert Forester
Mushet came to his rescue.

He suggested they should
remove all the carbon

and then add 1% back in.

It worked.

For the first time we could
mass-produce high-quality steel.

We now had a metal
that was strong enough

and tough enough
to fulfil our ambitions.

The breakthrough
made Bessemer's name,

but he had to be forced to acknowledge
the part Mushet had played.

In the end,
Bessemer had to agree to pay him

£300 a year for
the rest of his life.

With mass-produced steel we'd
cracked the problem of strength.

90% of the metal
we make today is steel.

It's allowed as to travel across the
globe by rail...

...by road...

...and by sea.

Strong, reliable steel enabled us
to build great cities.

The construction industry
would be nowhere without steel,

and the destruction industry
benefited just as much.

But steel was not the answer
to all our ambitions.

Aluminium would be
the metal of the next century.

The century when the secret inner world
of metals would finally be revealed.

The thing about metals is
they all look roughly the same.

But they're not the same.
This is steel and this is aluminium.

Aluminium is three times
lighter than steel.

Here was the perfect metal
to take us into the next age -

the age of flight.

Except for one thing - aluminium
is just not strong enough.

Scientists around the world began to
look for ways to make aluminium stronger.

Among them was the German
metallurgist, Alfred Wilm.

Wilm knew that our ancestors had
strengthened copper by mixing it with tin,

and what made steel strong was having
the right combination of iron and carbon.

So, he set about mixing aluminium
with other metals.

He finally ended up with
an alloy of aluminium, copper,

manganese and magnesium.

He named it duralumin.

And then he thought, when you want
to make really hard steel,

what you do is you quench it,
so he took those alloys

and he put them
in a furnace and he quenched them.

Here it is...

...and I'm going to quench it.

Now, once he'd quenched the alloys
the moment of truth came.

Would it be as strong as steel?

No.

And this happened time and time
and time and time again.

Until he could take
the disappointment no more.

He stormed out of his lab and...

...went boating for a few days.

But while he was
messing about on the river,

something remarkable happened.

Something that Wilm had neither
planned nor even imagined possible.

This is the same alloy.

The only differences is it's a week
later now, and watch this.

It's much, much stronger.

'And this is what Wilm found when
he returned from his boating trip.

'Without Wilm lifting a finger,
his alloy had transformed itself

'from a weak, bendy substance
into a strong, rigid one.

'It was almost as though
the lump of inert metal

'he had left behind was a living
thing that had changed over time.

'It had grown harder as it aged.'

What Wilm had discovered was
something called age hardening.

Let me show you how it works.

So, if this is a crystal
of aluminium,

we know that's really soft.

What we need is something
that's going to make it stronger.

Actually, he'd found an alloy
which, when you leave it over time,

tiny little crystals
grow inside the aluminium crystals.

They emerge out of a kind
of atomistic mist, and it's those

that harden the crystal, they make
it stronger, they reinforce it.

As new crystals grow,
they interfere with the lattice,

and the aluminium alloy's ability
to shuffle atoms and change shape.

This makes it harder and stronger.

Wilm had solved the problem of
how to make aluminium stronger.

And he had also revealed metals to
be mutable, almost living materials.

So many of the great discoveries
of science come by happy accident.

From Alfred Wilm's despair
came a new understanding of metals,

an understanding that would finally
allow us to conquer the skies.

His alloy, duralumin, was used to
make the fuselage of the Spitfire -

the only Allied aircraft to remain a front
line fighter throughout the Second World War.

War forced the pace,
with new and better alloys.

Peacetime brought the desire
for passenger flight.

We were about to push metals
harder than ever before.

In great secrecy, the De Havilland
company here in Hertfordshire

embarked on an ambitious plan to build
the world's first commercial jet aircraft,

to tame and harness changeable,
mutable metal

and build a plane strong
and reliable enough

to soar twice as high as man
had gone before.

The plane was
the ultimate in modern technology.

It went higher and faster,
and boasted a pressurised cabin

for the comfort of the jet age
passengers and crew.

It was also the most tested
aircraft of its time.

Mike Ramsden was one of
the test engineers on this,

"the De Havilland Comet.

Can you remember the moment
when you stood on an airfield

looking at this Comet taking off,
the comet you'd tested?

It was...

It was like watching something
from outer space, it was so...

...new, and it sounds corny,
doesn't it?

But there was nothing
else like it in the world.

When the crew were up
at double the height

and double the speed of propeller
airliners,

they just couldn't believe it,

being able to see both sides
of the Channel at the same time.

And flying high,
you had pressurised the cabin.

Yes, this was a very big
engineering challenge.

To pressurise the fuselage

so that human beings could
survive at that height.

It was the way to go,
it was the way to fly.

It was the way to arrive.

It seemed that a golden age
of air travel had dawned.

But it was about to
turn to disaster.

A year to the day after
the first passenger flight,

a Comet disintegrated in midair,
killing everybody on board.

Within months, two more Comets
had crashed into the Mediterranean.

The entire fleet was grounded.

There was something going on at the
heart of metal we didn't understand.

Did the whole staff,
you and all your workmates,

did you all feel responsible?

Did we feel guilty,
you mean, of killing 100 people?

Yes, is the short answer.

Finding the cause was now
the priority for Mike

and his colleagues.

They knew metal
was a mutable material,

that it could suffer from a damaging
phenomenon called metal fatigue.

They had tested
extensively for this.

But what they couldn't predict
were the effects

of this extreme new environment
and the pressurising

and de-pressurising of the cabin
needed for high altitude flight.

The real problem was
a combination of factors,

one of which was that this aircraft
had to go higher

than ever before, up five miles
high, which caused a compression

and decompression of the fuselage,

so you have it almost
breathing in and out, in and out,

every time it takes off and lands.

The stress of constant
pressurisation and de-pressurisation

eventually tolled on this aeroplane.

Metal will break
if you bend it often enough.

In the Comet's fuselage,
tiny fatigue cracks appeared.

What began as a very small fracture
close to a window

spread in to a catastrophic crack.

The whole aircraft came
apart mid-flight.

The cause was
a combination of metal fatigue

and concentrations of stress
within the fuselage.

It's a weird quirk of fate
that these windows were square

because that's exactly
the wrong shape

if you want to minimise
the concentration of stress.

So at the corners the stress
is all concentrated

and started forming little cracks,

it was those that were
the big problem.

Today we know that you mustn't have
square windows

in these kind
of pressure structures.

If you look at any aircraft today,
you'll never see a square window.

Comet changed everything.

New regulations would make sure
that metal was replaced

before it became fatigued.

But the most important lesson we
learnt was just how little we knew.

Extreme conditions were causing
extreme reactions

inside the metal
that we didn't understand.

We desperately needed
to see what was happening

deep inside the metal crystal.

One young scientist was about
to make a breakthrough

and I know him really well because a
few decades later

he was one of my lecturers here
at Oxford University,

Professor Sir Peter Hirsch.

Hirsch's team was one of the first
to take thin foils of metal

and look at them under a brand new
kind of microscope,

a transmission electron microscope,

which increased magnification
by tens of thousands.

Hirsch would finally see inside
the metal crystal

and what he found would send shock waves
around the world of material science.

Meeting up with
Professor Hirsch again,

he explained that in the 1950s
there were theories

about why metals behaved
as they did, but still no proof.

What was really needed
was an experimental technique

which was universally applicable
whereby you could see inside metals.

And that's what Hirsch discovered.

This is the film
he took of his original experiments.

He saw for the first time
deep inside the metal crystal,

where, incredibly,
the metal looked like it was alive.

Those moving little lines and loops
are the Mexican waves of atoms

shuffling across the metal crystal.

They're changing
the shape of the crystal.

Suddenly everything fell into place.

The technique revealed
a new micro-world, if you like,

inside a metal.

You suddenly saw
the inside of a metal

and all sorts of things
were revealed.

It was very, very exciting.

We were now in a position to prove

what had previously
only been guessed at...

That metals were dynamic crystals,

that these ripples were caused
by atoms

shuffling within the crystal,
changing the metal's shape.

This explained what we'd known for
centuries, but never fully understood...

Why metal would change shape

rather than crack
when it was hit with a hammer.

And also why it became stronger
when it was alloyed.

It showed that designing
the internal architecture of metal

was the key to progress.

Microscopy finally allowed us to
master the micro-world of metals.

Hirsch's breakthrough reignited
our passion and belief for metals.

We could start to design
our own metals,

and there was a huge flowering
of metallurgy.

There seemed to be no problem
we couldn't solve.

'And we were facing another.

'How to get a metal to work in the
most extreme environment on earth.

'A jet engine.'

Let me show you what 1 mean.

Inside jet engines,

is an incredibly difficult
place for metals to be.

Extremely hot temperatures.

Extremely high stress
they had to put up with.

So they had to design a new alloy

that could cope
with this environment.

And it was called "superalloy”.

So-called because it was so super.

Here's a bit of it here.

I'm going to pit it against
our old friend steel,

who, of course, we know and love.

I'm going to hang weights
off these two wires.

It's the same weight, in both cases,

and they're the same
thickness of wire.

So, now they're under
the same stress.

Now, I'm going to make it
harder for them,

because they'll have to hold that up
while under huge temperatures,

which means me
putting a blowtorch on them.

OK, are you guys ready? Let's go.

So, the steel wire succumbed
within a few seconds.

And that's only a fraction
of the heat inside a jet engine.

1 could be here all day
with the superalloy.

This superalloy can take this.

I know these metals all look the
same, but inside this superalloy

is the most-exquisite
microstructure,

that was designed for this purpose.

To control the movement
inside the metal,

and make it unbelievably strong
at high temperatures.

'The cubes of material
within the superalloy

'are called "gamma prime crystals".

'They sit within the alloy,

'affecting its ability
to change shape.

'Which makes it incredibly strong,

'even at temperatures
close to its melting point.'

That's pretty impressive,

and, as the jet age progressed,

scientists and engineers
pushed the technology,

to create more and more
powerful engines.

'Superalloys were some
of the strongest metals

'we had ever created.

'But the 21st century jet engine

'would push them to their limit.

'In this extreme environment,

'even superalloys
will change shape.

One of the things we love about
metals is their malleability.

When it's red hot,
it behaves like plastic.

You can make it into
whatever shape you want.

This is wonderful stuff
to make an engine out of.

But the problem is,
when you're making an engine

that needs to be operating
at temperatures

that are themselves red hot,

deep inside the engine,
you've got engine parts

that really musn't change shape.

'These turbine blades operate
at 1,700 degrees centigrade,

'and 10,000 RPM.

'If working in those conditions

'made them lengthen,
even a tiny bit,

a phenomenon known as "creep”,

'catastrophe would follow!

These engines are designed
with the precision of a watchmaker.

Here, at the back of the engine, you
can see the turbine blades rotating

within the casing.

If there's any creep
in those turbine blades,

they'll hit the casing, and the
whole thing will seize up.

And that must not happen.

Unlike with a car, there's no
hard shoulder in the sky.

'Creep can affect any metal.

'In extreme environments,

'the boundaries where crystals join

'can become routes that atoms travel
along, elongating the crystals!

So, what can we do about creep?

Metals are made of crystals,

and if the crystal boundaries
are the problem,

we can't take all the crystals out.

Or can we?

'This is the Rolls-Royce
turbine blade facility, in Derby.

'An entire factory dedicated
to making blades,

'which work right at the heart
of a 21st century jet engine.

'Here, they're actually
producing turbine blades

'from a single metal crystal,

'like a giant diamond of metal.

'These blades are
resistant to creep.

"Paul Withey is a casting specialist
at Rolls-Royce!

This is where we cast
the single crystal turbine blades.

This is the wax model of the blade.

What actually do is,
as part of the assembly process,

we'll fit in the spiral
onto the bottom of it,

to allow us to grow a lot of
crystals in at the bottom.

One crystal is selected
through a spiral,

and made to grow through the whole
of the rest of the blade.

'This is astonishing stuff.

'We've conquered creep,

'by growing our own metal.

'The crystal boundaries
that cause creep

'are prevented by the spiral tube,

'which stops all but one
metal crystal getting through,

"allowing that single crystal
Yo grow into the whole mould!

It's amazing that one of our
earliest activities with metal

was to cast it.

It's really where we came from,
as a civilisation.

Here we are, one of the most
sophisticated pieces of metallurgy

you can possibly do,
and it's casting again.

Yes. And it's actually using the
same process that was used

over 5,000 years ago, to make art
and religious artefacts,

and here today is being used to make

some of the most hi-tech engineering
components that you can find.

'In this age of single crystal
turbine blades,

'it seems that we've finally
understood how metals work,

'and how to make them work for us.

'Paul, and the engineers
at Rolls-Royce,

'are all upbeat about
the future of metals.

'But not everybody agrees.

'Some of my colleagues
in material science

'are beginning to think
we've outgrown metals.

'We've mastered them,

'and now we should move on
to other materials.

'But should we dismiss them
so easily?'

Metals are in everything around us.

The electricity that made
that kettle boil

came down a wire, and that wire
itself is made of metal.

Here's some.

It's copper.

So, the Copper Age is embedded
in our homes.

It delivers all our
electricity to us.

Then, the Bronze Age is still here,

for anyone who likes sculpture.

Beautiful, aesthetic material.

The Iron Age is here,

and steel?

We spent thousands of years honing
this material to be strong, tough,

and ultra-sharp.

Let's not forget the modern metals.

We fly around with aluminium,

but it's in our kitchens, too,

in this lovely, wafer-thin metal,

which is just extraordinarily
versatile.

But there's something a little sad
about the history of metals.

Each one starts out
as a revolution.

But, after a while, they recede,
and we take them for granted.

But 1 really don't think we should.

If it wasn't for metals,
we'd still be in the Stone Age.

Everything around us is shaped
by metals. Everything.

It's that step-by-step understanding
of the internal structure of metals,

the secret world
of the metal crystal,

that's been a huge
intellectual achievement.

Metals have driven
civilisation forward.

And, in doing so, they've defined
who we are as humans.

And that's something
we should be VERY proud of.

Subtitles by Red Bee Media Ltd