Tong Xuhang, Zhang Hao, Li D Y
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada.
Sci Rep. 2015 Feb 13;5:8459. doi: 10.1038/srep08459.
Claims are often found in the literature that metallic materials can be nanocrystallized by severe plastic deformation (SPD). However, SPD does not generate a well-defined nanocrystalline (NC) material, which can be achieved by subsequent annealing/recovery treatment. In this study, molecular dynamics (MD) simulation is employed to study the effect of annealing on structure and mechanical properties of cyclic deformed NC α-iron, which simulates SPD-processed α-iron. It is demonstrated that grain boundaries in the deformed NC α-iron evolve to a more equilibrium state during annealing, eliminating or minimizing the residual stress. The annealing treatment increases the system's strength by reducing dislocation emission sources, and improves material ductility through strengthening grain boundaries' resistance to intergranular cracks. The results indicate that the annealing treatment is an essential process for obtaining a well-defined NC structure with superior mechanical properties.
文献中经常有这样的说法，即金属材料可以通过严重塑性变形（SPD）实现纳米晶化。然而，SPD并不会产生一种定义明确的纳米晶（NC）材料，而这种材料可以通过后续的退火/回复处理来实现。在本研究中，采用分子动力学（MD）模拟来研究退火对循环变形的NC α-铁结构和力学性能的影响，该NC α-铁模拟了经过SPD处理的α-铁。结果表明，在退火过程中，变形的NC α-铁中的晶界会演变成更平衡的状态，消除或最小化残余应力。退火处理通过减少位错发射源来提高系统强度，并通过增强晶界对沿晶裂纹的抗性来改善材料的延展性。结果表明，退火处理是获得具有优异力学性能的定义明确的NC结构的必要过程。
