Tension-compression asymmetry in homogeneous dislocation nucleation stress of single crystals Cu, Au, Ni and Ni3Al

Molecular dynamics simulations are used to investigate the mechanism of the homogenous dislocation nucleation stress asymmetry under applied uniaxial tensile and compressive loads in single crystals Cu, Au, Ni and Ni3Al. The effect of temperature on the homogeneous dislocation nucleation stress and the ratio of tension-compression asymmetry are studied; furthermore, the ratios of tension-compression asymmetry are carefully investigated in term of unstable stacking fault energy and the atomic stacking configurations of the {111} slip planes. It is found that the tension-compression asymmetry of the homogenous dislocation nucleation stress can be attributed to that the atomic stacking configurations of the {111} slip planes are not symmetrical about the [11¯0] axis, which leads to nucleate different types of leading partial dislocations during compression and tension.