Influence of particulate size on creep properties of TiB-reinforced orthorhombic Ti-22Al-27Nb

摘要

Orthorhombic titanium alloys based on the intermetallic phase Ti{sub}2AlNb exhibit a higher strength and stiffness at temperatures above 500°C compared to conventional titanium alloys and a higher ductility than γ-TiAl intermetallics. However, the creep resistance needs to be improved. Therefore, attempts have been made to reinforce the known Ti-22Al-27Nb (at.-%) by titanium boride (TiB) particulates. Different processing routes allow the production of composites with varying TiB particulate size. The volume fraction of particulates has been kept constant at 6.5%. In this study the influence of particulate size on the steady state creep rate has been examined in the temperature range from 650°C to 700°C. The steady state creep rate 8μm TiB particulates is about one third of the steady state creep rate of the material with 40μm TiB particulates.