Molecular dynamics simulation of interaction between deformation twin and annealing twin in iron crystal

摘要

Molecular dynamics (MD) simulation is performed to study the interaction between deformation twin and annealing twin in iron crystal. Two samples are simulated in this paper. The annealing twin in each sample is considered pre-existing automatically and the deformation twin is formed in the process of mode-I type loading and emitted from the crack tip. The distances between the twin boundary of the annealing twin and the crack tip in two samples are different. The applied stress is imposed to the top and the bottom of each sample. When the stress intensity is K-I=0.94 MPa m(1/2), the partial dislocation is emitted from the crack tip of each sample, but the sample with larger annealing twin grain size will move a greater distance. As K-I is increased to 2 MPa m(1/2), the larger the annealing twin grain size is, the faster it will grow and the smaller the size of the deformation twin from the crack tip. That is to say, the size of the annealing twin will hinder the formation of the deformation twin and then affect the mechanical property of the material.