Magical metals, how shape memory alloys work - Ainissa Ramirez

翻译人员: Sanqiang Xiao 校对人员: Luyao Zou

Today we're talking about weird materials

今天我们要讲一讲

应用于于太空，机器人 和你口腔中的奇特材料。

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

I'm talking about shape memory alloys.

我要讲的是形状记忆合金。

Like the name says,

就像名字所说，

these are metals that remember different shapes.

这是些记忆不同形状的金属。

To understand how these metals work,

为了理解这些金属的工作原理，

we've got to talk about atoms and organizing.

我必须谈一下原子和结构。

Let's talk about atoms first.

让我们先来讲一下原子。

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

原子是一些你用眼睛 无法观察到的微小物质，

yet they make up everything in our world,

但是世间万物都是由它们组成的，

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

从你正坐着的椅子到你的手机。

Atoms have some surprising ways of behaving too.

原子同样有一些不可思议的表现。

We'll talk about that shortly.

我们将简短地说一下。

Now, how big is an atom?

一个原子有多大？

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

想象一下从你头上拉一根头发

and whittling it like a stick 100,000 times.

然后像削木头一样把它切10万次。

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

那些削下来的片段才像原子一样宽。

They're that small.

它们就那样小。

Now let's talk about atoms and organizing.

现在让我们来谈一谈原子和结构。

You may not know this, but atoms arrange themselves

你也许不知道这个， 但是原子自己的排布

similar to the way we humans arrange ourselves.

就像我们人类组织自己一样。

Sometimes they sit in rows, like we do

有时候它们排成一行，

on a bus or an airplane.

就像我们在公交车或在飞机上。

We call that seating arrangement a phase.

我们称那个座次排列为“相”。

Other times they sit diagonal from each other,

其他时候它们交错地排列，

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

有点像在电影院或运动场的座位。

This is another phase.

这是另一种“相”。

When atoms move from one seating to another

当原子从一种座位排列变成 另一种座位排列的时候，

this is called a phase change.

这就被称为“相变”。

Phase changes are all around us.

相变在我们身边无处不在。

You may already know about water's phases:

你也许已经知道水的“相”:

solid, liquid and gas.

固相，液相和气相。

Many other materials have phases like that too.

许多其他的材料也有类似的“相”。

Some of them have several solid phases.

其中一些拥有多个固态相。

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

好，回到我们之前提到的 那些形状记忆合金。

When we say that the metals remember their different shapes,

当我们说金属记得它们不同的形状时，

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

我们真正想说的是 它们记得原子的不同的座次排列。

of atoms. When the atoms rearrange,

当原子重新排列的时候，

the metal moves from one shape to another.

金属就从一种形状转换到另一种形状。

Let's look at a phase change in action.

让我们看看反应中的相变。

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

这里我有一根用镍和钛制成的金属导线。

This metal wire is a shape memory alloy,

这种金属导线是一种形状记忆合金，

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

我要用打火机的热量

using heat from a lighter.

让它在不同的形状之间转换。

Watch this.

瞧着：

I'm going to wrap this wire around my finger

我要将这根导线缠在我的手指上

and then heat it.

然后加热它。

Amazing!

好神奇！

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

当我加热它的时候， 那根导线变回了一条直线。

Let's try that again.

让我们再试一遍。

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

我将把它缠在我的手指上并加热。

Yep, that's still amazing.

是的，还是那么神奇。

Not only is it amazing, this is weird,

这不仅神奇，还很奇异，

because metals generally don't do that.

因为金属一般不会是那样的。

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

这是一根回纹针。 当我加热它的时候，什么也没发生。

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

我们看见的是， 记忆金属丝在受热时发生相变。

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

当金属丝冷却时，原子交错排列，

like the movie theater seating, we talked about before.

正如我们之间聊到的电影院座位一样。

We call this a monoclinic arrangement,

我们称之为单斜晶系排布，

and scientists will call this phase martensite.

科学家称之为马氏体。

When I heated up the wire,

当我们加热金属丝时，

the atoms moved into columns like airplane seating.

原子成列排布，像飞机座位一样。

This is a cubic arrangement.

这是立方晶体排布，

Scientists will call this phase austenite.

科学家称之为奥氏体。

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

当我们继续加热， 原子一点点移动，

and they'll do this forever.

不断重复。

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

他们这样协同移动， 就像不知疲倦地行军的军乐队一样

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

每一个都改变一点， 但当所有微小的改变加起来，

create a totally different pattern.

就会形成一个完全不同的排列。

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

这很酷，但我们可以把它应用到什么地方呢？

Well, if you look in the sky tonight,

如果你今夜仰望星空，

shape memory alloys are at work -

记忆金属就在那工作着。

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

在火星上，它们被用来 调节火星车的太阳能板，

so that it can study the environment.

使得火星车可以研究火星环境。

Like our metal straightened when it was heated,

正如我们通过加热使金属变直一样，

the metals holding the panels will move when electrically heated.

用于支撑平板的金属会由于电加热而移动。

When we stop heating the shape memory metal,

当我们停止加热记忆金属的时候，

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

平板会在反方向弹簧的作用下弹回。

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

回到地球，记忆金属被做成 动脉疏通术中的支架。

as stents, which are small collapsible springs

支架是一个小小的可折叠弹簧，

that force open passages.

用于撑开血管。

Shape memory alloys are also used to move robots,

记忆金属也被用于移动机器人，

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

玩具蝴蝶，牙齿矫正， 以及为了每次都能完美贴身

shape memory wires are used as underwires in bras.

记忆金属丝被用做胸罩的定型线。

Now you know Victoria's secret.

你知道维多利亚的秘密（内衣品牌）吧？

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

当把胸罩放到烘干机中， 它会变得焕然一新。

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

所以不论是在火星上还是在你的嘴里， 小小的原子移动，

can create huge changes,

能够产生巨大的变化。

and understanding the way atoms behave

了解原子作用原理，

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

让我们能制造改善世界的材料。