MECHANICAL PROPERTIES AND STRUCTURE OF OXYGEN-DOPED TANTALUM-BASE ALLOY

摘要

The tensile properties of oxygen-contaminated specimens were determined in vacuum at temperatures to 1316°C (2400°F). Specimens heat treated at 1700°C varied little in mechanical properties with oxygen content up to 3500 ppm. Beyond this level, the strength increased and ductility decreased abruptly with oxygen contami¬nation. Heat treated T-lll lost its ductility completely when the oxygen content reached 4200 ppm;in contrast, the as-doped T-lll was brittle at an oxygen level of only 800 ppm. An extremely fine coherent precipitate was observed in electron micrographs of as-doped specimens. It coarsened upon annealing at or above 1400°C and eventually formed discrete Hf02 particles. The structure and mechanical properties are correlated.