Computer experiment on deformation of nanocrystals of the chromium-niobium system. Part 1. Atomic-structural rearrangements

Abstract

Molecular-dynamic simulation of the process of stretching of chromium and niobium nanocrystals and chromium-niobium bicrystals was performed to a pair-potential approximation. Atomic mechanism of deformation and fracture is illustrated, which depends on the crystal orientation with respect to the acting force \(\bar P\). In the case of the initial orientation (100)⊥\(\bar P\), the reorientation mechanism (100)⊥\(\vec P\)→ (110)⊥\(\vec P\) is in action. In a bicrystal, it is niobium that deforms first and then the relay-race transfer of deformation from Nb to Cr takes place. With the initial configuration (110)⊥\(\vec P\), the fragmentation of the crystal and grain-boundary rearrangements are observed. Niobium crystallite in a bicrystal deforms only within the limits of elastic deformation whereas the deformation of chromium is of brittle-ductile mode. With the initial configuration (111)⊥\(\vec P\), the mechanism of pure brittle fracture is observed. In all cases, fracture of a bicrystal occurs along the interphase boundary. The causes of such atomic-structural transformations are explained.