Molecular dynamics simulation and in situ TEM study of crack healing

Abstract

In situ TEM observation of crack healing during heating was carried out in an α-Fe crystal, and the results indicated that a crack in α-Fe could completely heal when the temperature increased to a critical value. The molecular dynamics method was used to simulate crack healing during heating and/or under compressive stress in a Cu crystal. The simulation results showed that a centre crack in a Cu crystal would close under a compressive stress or by heating. The roles of compressive stress and heating in crack healing were additive. During crack healing, dislocations generation and motion occurred. If there were pre-existing dislocations around the crack, the critical temperature or compressive stress necessary for crack healing would decrease, and the higher the number of dislocations, the lower the critical temperature or compressive stress. The critical temperature necessary for a crack to heal depended upon the orientation of the crack plane.