Review of micromechanisms of plastic deformation in nanotwinned materials

Abstract

A brief review of the theoretical models which describe specific plastic deformation micromechanisms in nanotwinned materials is suggested. Novel nanotwinned materials (ultrafine- grained metallic materials with high-density ensembles of nanoscale twins within grains) exhibit simultaneously high strength and good ductility at room temperature. These characteristics of nanotwinned metals are very important for practical applications. However, micromechanisms responsible for the unique combination of high strength and ductility in nanotwinned metals have not yet been determined and represent the subject of intensive discussions. According to experimental data, the specific deformation mechanisms operate in nanotwinned materials. One of the specific deformation mechanisms in nanotwinned metals is widening of nanoscale twins due to stress-driven migration of twin boundaries. Another specific deformation mechanism in nanotwinned metals is detwinning process which was experimentally observed by several research groups in nanotwinned copper (Cu). In the framework of the models, micromechanism of nanotwin widening due to coherent twin boundary migration and detwinning micromechanism through migration of incoherent twin boundaries in nanotwinned materials are considered. Results of the theoretical models demonstrate good agreement with corresponding experimental data.