In-situ SEM observations of fracture behavior of BT25y alloy during tensile process at different temperature

Abstract In order to characterize the fracture behavior of BT25y alloy at different temperature, in-situ scanning electron microscopy of this alloy was performed during high temperature tensile deformation process. The results showed that microcracks mainly initiated at α/α and α/β interfaces during both 600 °C and 650 °C tensile process. However, the path of crack propagation varied at different temperature, it was related to the rapid decline in interface strength with deformation temperature increasing. When deformed at 600 °C, interface strength was higher than grain strength, cracks propagated into grain interior, the tensile specimen presented transgranular fracture characteristic. As the deformation temperature increasing to 650 °C, interface strength was lower than grain strength, cracks tended to propagate along interfaces, and the tensile specimen presented intergranular fracture characteristic. Mechanical performance was sensitive to deformation temperature, with the temperature increasing from 600 °C to 650 °C, the ultimate tensile strength fell by 200 MPa.