Microstructural and Mechanical Property Changes in the Ta-base T-111 Alloy with Aging

Abstract

The microstructural changes occurring in the Ta-base T-111 (Ta-8W-2Hf) alloy following 1100 h of aging at 1098, 1248 and 1398 K under inert atmosphere and its influence on the mechanical properties are reported. Microstructural evaluations were performed by optical, scanning electron microscopy and, for the first time, transmission electron microscopy. Electrical resistivity, hardness and tensile properties are compared between the as-annealed and aged samples. An increase in the amount of grain boundary precipitation with increasing aging temperature was found to decrease the electrical resistivity and material strength, leading to the eventual embrittlement of the alloy following aging at 1398 K.