Teacher Xu, Please Take Care of the Reckless Students in Your Class

At this time, within 30 classes.

The students were still disappointed, "We just said it, it's that simple!"

"Mr. Qu, is the answer correct?"

"Look! We've all done it, what do we do next? We study by ourselves? If we study by ourselves, it will be too boring!"

Qu Mingliang thought about it, "Okay! Then we won't brush the questions, let's learn more. This is some knowledge that my supervisor guided us to learn when I was a graduate student."

"Want to hear?"

Everyone gave face and nodded.

Qu Mingliang, "I'm not going to give up, I'll start straight away."

"You don't think the laws of physics are the building blocks of this world order, don't you?"

The classmates shook their heads, "Not necessarily?"

Qu Mingliang's face darkened instantly, "Cough, cough! Then I say this, it's people, most people, not including you, okay!"

The students nodded in satisfaction.

Qu Mingliang, "%￥#￥￥%..."

"You guys are getting better and better taught by Teacher Xu!"

"I go on... We are here today primarily to know and love five substances that defy the laws of physics."

"Memory metal is one of them."

Immediately, a classmate shouted, "Isn't this from the movie? Does it really exist in reality?"

Qu Mingliang is extremely serious but responsible, "Yes, it exists!"

"Memory metals are also called shape memory alloys."

"In the 70s, an alloy with shape memory function appeared in the world material science."

"Memory alloy is a very special metal strip, it is very easy to bend, we put it in a glass jar with hot water, the metal strip rushes forward; put it in cold water, the metal strip is It was restored to its original state. In a glass jar filled with cold water, a spring was stretched, and when the spring was placed in hot water, the spring automatically closed again."

"The spring returns to its original shape in cold water, while in hot water, it contracts. The spring can be stretched and contracted an infinite number of times, contracted and then pulled open."

"These are made of a smart metal with a memory that has two relatively stable states of its microstructure, and at high temperatures the alloy can be transformed into any shape you want, and at lower temperatures The alloy can be stretched, but if you reheat it, it will remember its original shape and change back."

"This material is called memory metal, and it's a nickel-titanium alloy."

"For example, a helical superalloy, after being annealed at high temperature, has a helical shape."

"At room temperature, even if you use a lot of force to straighten it, as long as it is heated to a certain metamorphosis temperature, the alloy seems to remember something and immediately returns to its original spiral shape, which is what happened?"

"Does alloys also have the memory of humans?"

Qu Mingliang was full of self-confidence. Looking at the whole class, he finally found a field that these little ancestors had not touched.

"Who can tell me? Why is this?"

"You don't know, do you?"

"Actually..."

Before Ke Qu Mingliang could be silent for a few seconds, Qian Mengmeng said directly, "Is this just using the law that the crystal structure of certain alloys changes with temperature when they are solid?"

"For example, Nitinol has a different crystal structure above 40°C and below 40°C, but when the temperature is changed around 40°C, the alloy shrinks or expands, causing its morphology to change."

"I'll be more specific."

"Here, 40°C is the transformation temperature of nickel-titanium memory alloys."

"Various alloys have their own metamorphosis temperatures."

"The above-mentioned superalloy has a very high transformation temperature. At high temperature it is spiraled and it is in a stable state."

"When it was forcibly straightened at room temperature, it was in an unstable state, so as soon as it was heated to the metamorphic temperature, it immediately returned to its original stable spiral shape."

Qu Mingliang opened his mouth wide and was speechless.

Nima!

How do you know everything? !

"That's what Teacher Xu told you too?"

Qian Mengmeng stuck out her tongue, "I've encountered it before, so I asked Teacher Xu."

At this moment, Qu Mingliang has a feeling of "both Sheng Yu and He Shengliang" rolling over.

"Hey……"

"Okay, I don't believe you know the next one. Guess what the second one is?"

The classmates looked at Qu Mingliang indifferently.

Qu Mingliang, "Uh..."

Shi Leiluo said, "Teacher, if you want to say something, just say it quickly, if you don't say it, we'll do something else?"

Qu Mingliang became anxious, "Don't, don't! I said! I said!"