In-situ SEM study of temperature dependent tensile behavior of wrought molybdenum

Abstract Molybdenum and its alloys are widely used in electronic industries, metallurgies, aerospace, and nuclear engineering, etc. The applications frequently involve environmental conditions where both the loading and the temperature change. Uniaxial tension tests are carried out for wrought molybdenum under a scanning electron microscope (SEM) at a temperature range from 300 °C to 750 °C. The results indicate that both the tensile strength and the fracture strain for wrought molybdenum are peaked at 300 °C within the tested temperature range. With further increases of temperature, the fracture strain decreases monotonically. In-situ SEM observations reveal the slip band evolution, the deformation of grains, as well as the crack formation. At elevate temperature, cross-slip occurs at a lower strain, and the entanglement and intersection of slip bands lead to the formation of cell structures. Combining the SEM surface morphologies and the fractographs, one concludes that the fracture type is mainly of cleavage when uni-axially tensioned at 300 °C, albeit extensive plastic deformation occurs prior to fracture. The fracture type becomes mixed cleavage and plastic shear when uni-axially tensioned at 450 °C, 600 °C, and 750 °C.