Microstructure and Mechanical Properties of Ti-6Al-4V Rods Fabricated by Powder Compact Extrusion of TiH2/Al60V40 Powder Blend

摘要

Nearly fully dense Ti-6Al-4V rods were fabricated by powder compact extrusion of TiH2/Al60V40 powder blend. The microstructure, mechanical properties, and fracture behaviors of the Ti-6Al-4V rods extruded at various temperatures from 1100 degrees C to 1400 degrees C were investigated. The results showed that with the extrusion temperature of 1100 degrees C, undissolved V-rich particles still existed in the microstructure, but they disappeared once the extrusion temperature increased to 1200 degrees C. Nearly complete dehydrogenation of TiH2 was achieved during rapid induction heating, holding, and extrusion. With increasing the extrusion temperature, prior grain sizes and / lamella colony sizes increased dramatically, while the change of lamella thickness was much less significant. The correlation between microstructure and mechanical properties suggests that / lamella interfaces, instead of colony boundaries, are responsible for strengthening. The coarse prior grains whose sizes reached 150m had a deleterious effect on the tensile ductility due to localized deformation, as evidenced by the intergranular fracture. The rod extruded at 1200 degrees C had the best elongation to fracture of 9.3pct while still keeping a high yield strength of 969MPa and ultimate tensile strength of 1102MPa.