Deformation Mechanisms, Microstructure and Mechanical Properties of Nanoscale Crystalline and Noncrystalline Materials in Different Temperature Ranges

Abstract

ABSTRACTA review of the influence of nanoscale structural elements on the mechanical properties of crystals, quasicrystals, and metallic glasses (MG) is presented. Temperature ranges of cold, warm, and hot deformation are distinguished for crystalline materials, but a nanocrystalline (NC) structure may be formed by severe plastic deformation in the temperature ranges of warm and hot deformation. The plasticity characteristic obtained by indentation can be used for the characterization of low-ductile NC materials. The main features of the plastic deformation mechanisms of NC materials, including results obtained by molecular dynamic simulation, are considered.For MG, the following two problems are discussed: the comparison of the yield stresses for NC and MG and the possibility of strengthening of MG by disperse crystalline nanoscale particles.Quasicrystals with nanosize grains, which are also called nanoquasicrystals (NQC), form a separate class of materials. The mechanical properties of NQC and crystalline materials strengthened by NQC particles are analyzed. Dispersion hardening of metals by NC particles was the first application of nanoscale structures for structural materials. New possibilities of such strengthening are considered.