High temperature deformation behavior of the molybdenum alloy TZM

Abstract

The molybdenum alloy TZM (Mo-0.5wt%Ti-0.08wt%Zr) is a commonly used constructional material for high-temperature applications. It is well known that molybdenum and its alloys develop a distinct subgrain structure and texture during hot deformation. These microstructural aspects have a significant effect on strength at elevated temperatures. It was observed that with proceeding primary recrystallization and therefore with disappearance of subgrains the yield strength drops almost to the level of pure molybdenum. The aim of the present work was to investigate and describe the strain hardening of hot deformed TZM on a microstructural basis. For this purpose sintered and prerolled TZM rods were recrystallized and each of them deformed to a specific degree of deformation afterwards. Especially the evolution of disorientation distributions was analyzed by electron backscattering diffraction (EBSD) and used to describe the work hardening effect. The yield strength was determined by tensile tests between room temperature and 1473 K. By analyzing disorientation profiles the formation and evolution of geometrically necessary and incidental dislocation boundaries could be observed. A model developed by Pantleon was used to describe the work hardening of TZM.