Materials science The tough get going…

摘要

Most materials become weaker and break when subjected to increasing strain. But there are exceptions: strain stiffening is common in complex biological systems, where it protects soft tissues from excessive deformation. The phenomenon is rare in crystalline solids, but Chao Jiang and Srivilliputhur Srinivasan report quantum mechanical calculations that reveal reversible strain-stiffening behaviour in iron carbide (Fe_3C) and aluminium borocarbide (Al_3BC_3), operating through two different mechanisms. The findings for Fe_3C are of particular technological interest. Also known as cementite, Fe_3C is a precipitate in carbon steels. Thus, these results could contribute to models for predicting the hardness of steels and other structural materials. Unexpected strain-stiffening in crystalline solids