Plastic Flow through Widening of Nanoscale Twins in Ultrafine-Grained Metallic Materials with Nanotwinned Structures

摘要

A theoretical model is suggested which describes plastic flow through widening of nanoscale twins in nanotwinned metals (ultrafine-grained metallic materials containing high-density ensembles of nanoscale twins within grains). In the framework of the suggested model, widening of pre-existent growth twins under mechanical load carries plastic deformation and leads to rearrangements of defect structures at junctions of twin and grain boundaries. With these factors (changes in twin widths, and rearrangements of defect structures), we calculated the yield stress as a function of twin thickness in nanotwinned metals in the situation where widening of nanoscale twins significantly contributes to plastic flow. Our theoretical results and their comparison with corresponding experimental data (reported in the literature) are discussed.