Microstructure and high temperature tensile properties of powder metallurgy Mo−Re alloys

Abstract

Mo−14Re and Mo−42Re alloy bars were prepared by powder metallurgy and hot press working. The microstructure, phase composition, and tensile properties at room and high temperature were observed and tested, and the fracture mechanism of Mo−Re alloys was analyzed, combined with the fracture morphology. The results show that, after the hot press working, the Mo−Re alloy grains change from equiaxed to elongated fibrous, and the relative density of alloy bars is more than 99.6%. The solid solution of Re in Mo reduces the lattice constant of Mo−Re alloy from 3.1384 Å of Mo−14Re to 3.1304 Å of Mo−42Re, leading to the increase of lattice distortion. The room and high temperature strength of Mo−Re alloys are greatly improved with the increase of Re mass fraction from 14% to 42%. With the increase of test temperature, the strength of Mo−Re alloys decreases, the elongation of Mo−14Re alloys decreases slightly, while that of Mo−42Re increases. The room temperature fracture of Mo−14Re alloys exhibits a wood-grain tearing fracture, the fracture at 1100~1300 ℃ is dimple, and the plastic deformation is mainly caused by grain boundary slip at 1500 ℃. The room temperature fracture of Mo−42Re alloys shows a transgranular fracture, the fracture at 1100~1500 ℃ is completely dimpled, and the plastic deformation at high temperature is provided by the non-uniform deformation produced by dimple.

Keywords

• mo−re alloys
• microstructure
• tensile property
• fracture morphology