Research on Preparation Methods and Phase Transformation of High Quality Ti-48Al-2Cr-2Nb Alloy Powder

Ti-48Al-2Cr-2Nb alloy powder was prepared by plasma rotating electrode method. The phase transformation microstructure of the alloy powder was researched. The results show that the powders are mainly distributed in 75-200 μm,the median particle size is 135 μm. The oxygen content in the powder decreases with the increase of powder particle size,when the powder particle size exceeds 106 μm, the oxygen content of powder does not change significantly with the increase of powder particle size, but the contents of nitrogen and hydrogen does not change significantly with the increase of powder particle size. The percentage of hollow powder increases with the increase of powder particle size, and the maximum value is about 0.6%. The powder is rapidly solidified cellular crystal or cellular dendrite and the phase composition of the powder are mainly α2（Ti₃Al） phase and a small amount γ（TiAl） phase. When the heating temperature reaches 701 ℃, the powder begins to transform from α2 phase to γ phase; when the temperature reaches 1151℃, the α2+γ transforms into high temperature αphase; when the temperature reaches 1278℃, α+γ phase transforms into α phase.