In-Situ Study of High Temperature Tensile Fracture Mechanism of Mar-M247 Alloy

The dynamic microstructure evolution and fracture mechanism of Ni-based cast superalloy Mar-M247 during tensile test at room temperature, 400 degrees C and 760 degrees C are investigated by an in-situ SEM high temperature tensile stage. The in-situ tensile test results show that the yield strength and ultimate tensile strength decrease slightly, and the tensile plasticity increases slightly from room temperature to 760 degrees C. There is no slip band during in-situ tensile test at room temperature; and there is only a small amount of slip bands near the fracture surface at 400 and 760 degrees C tensile test. With the increase in tensile temperature, the fracture mechanism does not change, and all of them are ductile transgranular fracture. Microcracks mainly originate from the rupture of carbides dispersed in the grains and on the grain boundaries.