MIT is working on metal, which he fixes his crack - Gazeta Wyborcza

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When the metal starts to crack, further pressure will make you burst in full, is not it? As it turned out, not always. Research conducted at MIT by Prof.. materials engineering Michael Demkowicz show that in certain specific cases, the metal may fracture heal itself. Without any human intervention.

When the team of prof. Demkowicz first observed this phenomenon, he decided to repeat the experiment. Scientists thought that had to occur somewhere mistake. – Once again we saw, we started to wonder why this is happening – says prof. Demkowicz.

The answer lay in the interaction of atoms arranged randomly located on the border of individual grains of metal from its microcrystalline structure. – The object of the study was with us nickel alloys basic ingredient used, among others, in-built offshore oil platforms – says the professor.

Scientists have created a computer model of the entire structure, and found that there is a mechanism for plugging cracks under any pressure.

– Most metals is composed of very small crystal grains. Their size and placement can affect the properties of the material as even strength – explains Professor. Demkowicz. – Under certain conditions, the boundaries of these grains can move. So far, this phenomenon was known in liquid metals. A decade ago, it turned out that this is a solid metal – he added.

According to the property of self-healing of cracks formed when the crystal structure is fraught with some kind of defect. – Specifically, the so-called. wedge dislocation, where the grain boundary penetrates partially in its structure – says prof. Demkowicz.

This defect results in the formation of internal tension in the affected area of ??the material. – Tensions strong enough that he is able to reverse the normal effect of external pressure and make her crack zasklepi?o instead to grow – explains the scientist.

The team plans to begin research on the design of metals and alloys with deliberately placed in them dislocations wedge. Material would automatically remove cracks under pressure normally acting for him in various applications.

– We mean alloys for aircraft construction or drilling platforms. Our findings may help wherever parts are subjected to high forces. Metal fatigue, produced by collecting in it for a long time nanop?kni?cia is the most common cause of damage in structures made of him – said prof. Demkowicz. – If we can develop a method of forming a metal capable of self-removal of such cracks, we can greatly increase the life and safety components that are made from them – he concludes.