Influence of Rare-Earth Additions on Properties of Titanium Alloys. Room-Temperature Tensile Properties and Fracture Toughness of Ti-6Al-4V with Erbium,Yttrium,and Yttria Additions.

摘要

The influence of additions of 0.1 wt% Er, 0.02 wt% Y, 0.05 wt% Y, and 0.038 wt% Y2O3 on the room-temperature tensile properties and fracture toughness of Ti-6Al-4V was studied. The alloys were cast by consumable-electrode arc-melting in vacuum. Er and Y were added in the form of Ti-25Er and Ti-25Y master alloys, and Y2O3 was added in the form of a fine powder. The alloys, after being forged and rolled, had only about half the nominal concentrations of rare-earth additives. The rolled plates were given various heat treatments to observe the combined effects of microstructure and rare-earth additives. The rare-earths effect grain refinement. The room-temperature tensile properties and fracture toughness of Ti-6Al-4V are not significantly altered by the rare-earths. The crystallographic texture developed during rolling also is unaffected by the rare-earth additives, although Y and Y2O3 effect an increased sharpness of near-transverse-basal texture components in alpha-beta annealed alloy. The uniform elongation of Ti-6Al-4V under tensile stress at high temperatures is increased by Er and Y additions. The high-temperature compressive stress-strain characteristics of heat treated Ti-6Al-4V are not altered by Er and Y. (Author)