Molecular dynamics simulation of microcrack healing in aluminium
摘要
The molecular dynamics method is used to simulate microcrack healing during heating or under com-pressive stress. A center microcrack in an Al crystal could be sealed under a critical compressive stress or by heating it over a critical temperature. During microcrack healing, dislocation and vacancy are generated and moved, and sometimes twin appears. The critical temperature necessary for microcrack healing depends upon the orientation of the crack plane. For example, the critical temperature of the crack along the (111) plane is the lowest. When there are pre-existing dislocations around the microcrack, the critical temperature necessary for microcrack healing will decrease. The energy condition for crack healing is , where a is the applied compressive stress, a the length of the crack, v the Poisson' s ratio, E the Young' s modulus, UT heat energy driving crack healing, A the area of the crack, γthe surface energy, and γP the plastic deformation work. Pre-existing dislocations can reduce γP.