Effect of Mg2Si particles on low-temperature fracture behavior of A356 alloy

The variation of tensile properties of A356alloy at 20 °C~−60 °C has been investigated. the distribution of dislocation slip bands near the fracture surface was studied by scanning electron microscopy SEM. Dislocation distribution was observed by transmission electron microscope TEM. The elastic stress field near the Mg2Si phase at low temperature was analyzed by ANSYS. When the temperature is decreased from 20 °C to −60 °C, the tensile strength and yield strength of A356 alloy increase and the elongation decreases. Under the effect of cold shrink, the elastic stress produced by the alloy matrix hinders the movement of the dislocation. In low temperature environment, the edge dislocation whose excess half atom facing toward Mg2Si experiences a repulsing force. On the contrary it experiences a gravitational force.