纳米多晶金属的晶界设计及强韧化研究进展

Nanocrystalline polycrystalline metals exhibit many unique mechanical properties due to the high fraction volume of grain boundaries,such as high strength and hardness,good wear resistance,and excellent fatigue resistance. However,the problems of intergranular softening and grain boundary brittleness brought by the abundant grain boundaries seriously restrict their practical application in the field of structural engineering. Therefore,how to precisely design the rich and common grain boundaries in nanocrystalline polycrystalline metals,as well as establish new theories and methods related to the variation of mechanical properties,has become a hot and difficult research topic in the field of materials science and nanomechanics. In this paper,taking face-centered cubic structure metals as an example,the recent research progress in improving mechanical properties of nanocrystalline materials through grain boundary engineering was comprehensively reviewed. Moreover,several major methods in manipulating grain boundaries in present and their effects on strength and plasticity are emphasized,then underlying strength and toughness mechanisms were comparatively analyzed. Finally,the existing problems and challenges in the research process of this subject were summarized,and the future development direction was prospected.