Magical metals, how shape memory alloys work - Ainissa Ramirez

神奇金屬：形狀記憶合金的原理 - 艾尼薩拉米瑞茲 (Ainissa Ramirez)

譯者: Jephian Lin 審譯者: Allen Li

今天我們要談一種詭異的材質

Today we're talking about weird materials

that we use in space, in robots and in your mouth.

使用在太空、機器人、和你嘴裡

它是「形狀記憶合金」

I'm talking about shape memory alloys.

就跟它的名字一樣

Like the name says,

這類金屬可以記住不同的形狀

these are metals that remember different shapes.

要了解這類金屬的原理

To understand how these metals work,

我們必須先談談原子和排列

we've got to talk about atoms and organizing.

Let's talk about atoms first.

我們從原子說起

原子是很小的物質，肉眼看不到

Atoms are tiny bits of matter that you cannot see with your eye

但它組成了世界的所有東西

yet they make up everything in our world,

from the chair that you're sitting on to your cell phone.

從你坐的椅子、到用的手機都是

Atoms have some surprising ways of behaving too.

原子也有些令人驚奇的行為

We'll talk about that shortly.

待會兒就會談到

Now, how big is an atom?

先談談原子有多大？

Well, imagine pulling one of your hairs out of your head

想像從頭上拔下一根頭髮

and whittling it like a stick 100,000 times.

把它當棍子，削成十萬根細絲

One of those shavings would be the width of an atom.

每根絲就大約和原子一樣寬

They're that small.

就是這麼小

Now let's talk about atoms and organizing.

接著談原子的排列

You may not know this, but atoms arrange themselves

你也許不知道 不過原子自己會排列

similar to the way we humans arrange ourselves.

就像我們人類會自己排列那樣

Sometimes they sit in rows, like we do

有時候它們會排排坐

on a bus or an airplane.

像我們坐公車或搭飛機那樣

We call that seating arrangement a phase.

我們把這種座位排列稱作「相態」

Other times they sit diagonal from each other,

也有時候它們會斜角坐

sort of like seats in a movie theater or sports stadium.

像電影院或體育館的座位那樣

This is another phase.

這是另一種相態

When atoms move from one seating to another

當原子從一種坐法變成另一種

this is called a phase change.

就叫作「相變」

Phase changes are all around us.

相變無所不在

You may already know about water's phases:

你也許聽過水的三相：

solid, liquid and gas.

固態、液態、還有氣態

Many other materials have phases like that too.

許多物質也有類似的相態

有些固體就有數種不同相態

Some of them have several solid phases.

回到我們剛說的形狀記憶合金

OK. Back to those shape memory alloys we mentioned before.

當我們說這些金屬 會記住不同的形狀

When we say that the metals remember their different shapes,

what we're really saying is they remember different seating arrangements

我們真正的意思是 它們會記住不同的

原子座位排列 當原子重新排列時

of atoms. When the atoms rearrange,

the metal moves from one shape to another.

金屬會改變形狀

Let's look at a phase change in action.

我們來看看，相變怎麼進行

這是根鎳鈦合金的金屬絲

Here I have a metal wire that is made out of nickel and titanium.

它是種形狀記憶合金

This metal wire is a shape memory alloy,

and I'm going to make it switch between its different shapes

我要改變它的形狀

using heat from a lighter.

用打火機的熱量

Watch this.

看著

I'm going to wrap this wire around my finger

我先將金屬絲在手指繞幾圈

and then heat it.

然後加熱

Amazing!

太神奇了！

That wire returns to a straight line, when I heat it.

加熱後，金屬絲變回直線了

再試一次

Let's try that again.

I'm going to wrap it around my finger, and heat it.

我先在手指繞幾圈，然後加熱

沒錯，還是一樣神奇

Yep, that's still amazing.

Not only is it amazing, this is weird,

不只神奇，而且詭異

because metals generally don't do that.

因為一般金屬不會這樣

Here's a paper clip. When I heat it, I get nothing.

我加熱迴紋針，什麼事也沒發生

What we're seeing is the shape memory wire changing phases when it gets hot.

我們看到的是形狀記憶金屬絲 受熱產生相變

當金屬絲是冷的時候 原子是斜向排列

When the wire is cold, atoms are in a diagonal arrangement,

like the movie theater seating, we talked about before.

像剛剛說的電影院座位那樣

We call this a monoclinic arrangement,

我們稱之為「單斜排列」

科學家把這個相態稱作「馬氏體」

and scientists will call this phase martensite.

當我把金屬絲加熱

When I heated up the wire,

the atoms moved into columns like airplane seating.

原子就變成像飛機座位那樣排排坐

This is a cubic arrangement.

這叫作「立方排列」

Scientists will call this phase austenite.

科學家則稱為「奧氏體」

So when we added the heat, the atoms shifted positions seamlessly,

所以加熱時 原子就順暢的移動位置

and they'll do this forever.

而且永遠會這樣

They have this coordinated motion, just like members of a tireless marching band.

它們有這種協調運動 就像是個永不疲倦的軍樂隊

每個人都移動一點點 這些小改變加起來

Each makes a small shift, but all together those small shifts

create a totally different pattern.

就變成完全不同的隊形

這很酷，但哪裡有用到這些材料？

So that's pretty cool, but where do we use these materials?

Well, if you look in the sky tonight,

如果你今晚看看天空

shape memory alloys are at work -

形狀記憶合金正在工作…

on Mars. They're used to move panels on the Mars rover,

在火星的探測車上，移動太陽能板

so that it can study the environment.

讓探測車有能量研究環境

就像金屬絲加熱時變直

Like our metal straightened when it was heated,

the metals holding the panels will move when electrically heated.

支撐太陽能板的金屬 用電加熱就會移動

When we stop heating the shape memory metal,

若停止加熱形狀記憶金屬

the panel will return back, due to an opposing spring.

太陽能板就被彈簧拉回原位

Back on Earth, shape memory alloys are used to open up clogged arteries

回到地球上，形狀記憶合金 也被用來撐開阻塞的動脈

as stents, which are small collapsible springs

它叫作「支架」 是個可壓扁的小彈簧

that force open passages.

會強迫動脈打開

Shape memory alloys are also used to move robots,

形狀記憶合金也被用來 移動機器人、

toy butterflies, teeth in braces, and for a perfect fit every time,

玩具蝴蝶、牙齒矯正器。 且因可以一直保持完美形狀

shape memory wires are used as underwires in bras.

也用在胸罩下方的金屬絲

Now you know Victoria's secret.

「華歌爾」和「黛安芬」的胸罩

By popping a bra into the dryer, it'll be brand new every time.

丟進烘衣機，就會恢復原來形狀

所以無論在火星、或你嘴裡 原子小小的移動

So whether it's on Mars or in your mouth, small atomic movements

can create huge changes,

可造成大大的改變

and understanding the way atoms behave

而對原子行為的了解

allows us to make materials that make our world a better place.

使我們可做出讓世界更美好的材質