纳晶金属的力学行为

纳晶金属特指晶粒尺寸在($1 \sim100)$\,nm块体金属材料,其在力、热、声、电、磁等方面有着潜在应用,对它的制备、表征和模拟是材料科学及相关领域的重要前沿.由于纳晶金属结构简单,影响性能的因素相对单一,因而对结构与性能之间关系的理论研究具有深刻的意义.纳晶金属三维细观拓扑结构与常规多晶体类似,但由于晶粒尺寸减小,晶界原子体积比增加,因此呈现出与粗晶金属不同的性质,并且当微观物理过程的特征尺度大于晶粒尺寸时,与其对应的性质也将受到晶粒或者晶界的调制作用.本文从制备、力学性能和塑性变形机制3个方面介绍了纳晶金属力学的部分最新进展,并讨论了结构特征与力学性能之间的关系. 

MECHANICAL BEHAVIOR OF NANOCRYSTALLINE METALS

Nanocrystalline metals are defined as metals with an average grain size in the (1-100) nm range. Because of their potential applications in mechanics, thermodynamics, acoustics, electronics, and magnetics, etc, their manufacture and research have been an important frontier, both in materials science and the related fields. Their relative simple microstructures and characterizing parameters impose a fundamental meaning in theoretical studies. The three-dimensional topology of nanocrystalline metals is similar to their conventional counterparts. However, for the extremely small grain size, the volume fraction of grain boundaries increases greatly, which will lead to different mechanical properties from coarse-grained metals. Moreover, when the characterized lengths of the microscopic physical processes compare to the grain size, the related properties will be modulated and thus different from well-known ones. In this paper, we present some new developments of preparation, mechanical properties and plastic deformation mechanisms in nanocrystalline metals and discuss the relationships between microscopic structures and mechanical properties.