SYNTHESIS OF Ti-47Al-2Cr-2Nb ALLOY THROUGH ELEMENTAL POWDER METALLURGY

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Under the protection of Ar, TiAl base alloy of high density has been prepared through hot pressing elemental Ti, Al, Cr and Nb powders at elevated temperatures. The microstructure, phase constitution and composition were analyzed through optical microscopy, SEM, EDAX, and XRD techniques. Results show that TiAl base alloy with near fully lamellar microstructure and a mean colony size of 60 μm, can be obtained after hot pressing at 1 300 ℃ for 1 h; however, incomplete diffusion of Nb element exists in the microstructure. Through subsequent isostatic hot pressing (HIP), the material density can increase and the homogeneity of alloy elements can be improved simultaneously. Furthermore, it has been found that the initial microstructure of the alloy has great influence on its microstructure after HIPping in ( α+γ ) field.