What is the overburdened dark matter

Special crystals become even stronger under load

If brittle crystals are stressed, they can easily break. But that does not apply to all crystalline materials. On the contrary, a compound of iron and carbon, called cementite, can become stronger and stronger the more it is under pressure. Materials researchers predicted this behavior with computer simulations, in which the bonding behavior of the atoms to one another was revealed. On this basis, about which the researchers report in the journal “Nature”, new ways of synthesizing extremely solid materials could now be found.

Cementite crystals

"Our discovery changes previous knowledge of solid materials and will have a major impact on the design of structural materials," says Chao Jiang of Los Alamos National Laboratory. Together with his colleague Srivilliputhur Srinivasan, he developed a computer program to simulate the atomic bonds in crystals. The possible crystal structures and the quantum mechanical behavior of the atoms involved were taken into account. The calculations showed that under extremely high pressures of the order of tens of gigapascals, the cementite crystals can build up additional cross-connections to one another and thereby gain strength. The simulations also showed a similar behavior for a carbide compound with aluminum and boron.

These predictions about increasing strength could now be checked in experiments. This requires special high-pressure equipment in which hydraulic mechanics can press extremely hard on a material. With such hydraulic presses, the soft carbon material graphite could be pressed so hard that tiny diamond crystals were formed. If these experiments succeed, the manufacture of a new class of high-strength materials would be conceivable.