The stress-state within individual grains in a polycrystal determine the fate of the aggregate including mechanical failure. By tracking the evolution of the stress tensor throughout the elastoplastic transition, large rotations of the stressstate, which have long been theorized to occur, are observed experimentally for the first time. These stress rotations (∼15°) are more than an order of magnitude larger than the concomitant crystallographic lattice reorientations (∼0.9°) well-known to occur during metal plasticity. Furthermore, these rotations are accompanied by a decrease in stress triaxiality within certain grains, promote strain softening, and set the stage for failure at an early stage of deformation. These results provide a completely new perspective through which to contemplate the question of “hot-spots” responsible for failure of high-performance structural materials.

多晶中单个晶粒内的应力状态决定了聚集体的命运，包括机械故障。通过在整个弹塑性转变过程中跟踪应力张量的演变，第一次通过实验观察到应力状态的大旋转，这种旋转长期以来一直被理论认为会发生。这些应力旋转（~15°）比金属塑性过程中众所周知的伴随晶格重新取向（~0.9°）大一个数量级以上。此外，这些旋转伴随着某些晶粒内应力三轴性的降低，促进了应变软化，并在变形的早期阶段为失效奠定了基础。