A COMPARISON OF THE MICROSTRUCTURE AND HIGH TEMPERATURE TENSILE PROPERTIES OF A NOVEL P/M Mo-Hf-Zr-Ta-C ALLOY AND TZM

摘要

The microstructure and elevated temperature quasi-static tensile yield and ultimate strength observed in a novel, forged Mo-based alloy (Mo-0.25Hf-0.25Zr-0.25Ta-0.025C) has been analyzed and compared to a standard forged TZM composition (Mo-0.50Ti-0.08Zr-0.02C). The novel material exhibits the desirable forging characteristics typical of the widely used TZM composition yet possess a higher ultimate strength and 0.2% offset yield strength in both the stress-relieved and recrystallized conditions over a 400° -1200℃ temperature range. The greater strength measu ed in the novel composition has been attributed to the combined effects of precipitation of Hf, Zr and Mo-(carbide) precipitates that strengthen the matr x in the classical Orowan fashion and improved resistance to recrystallization after high temperature exposure. Elevated temperature creep behavior, not addressed in the study presented here, will be reported on in a subsequent analysis.