High Temperature Properties of TiAl Alloys Produced by Elemental Powder Metallurgy

초록

Through the fundamental research works in the last decade, it has been realized that elemental powder metallurgy (EPM) is a viable approach to produce sound TiAl alloys of dependable quality. Alloy design efforts resulted in a variety of chemical compositions such as Ti-46.6Al-1.4Mn-2Mo with assorted minor additions of C or Y. Fully lamellar microstructures with extremely fine lamellar thickness could be obtained an were shown to have about 3% in tensile elongation and close to 700MPa tensile yield strength at room temperature. Furthermore, in high temperature air tests, the alloys exhibited a rather low secondary creep rate as well as a good oxidation resistance at 800oC. The attractive properties have been attributed to the finescale lamellar microstructure, precipitation hardening and the formation of a surface oxide phase impervious to oxygen penentration.