粉末注射成形钛铝烧结工艺研究

Sintering of TiAl Injection Molding

利用Ti-47.5Al-2.5V-1.0Cr（%）气雾化预合金粉末为原料,采用注射成形工艺制备了TiAl合金材料,研究了TiAl合金烧结工艺以及烧结工艺对烧结体显微组织、密度和性能的影响。结果表明：烧结体在超固相线液相区烧结得到密度最高。在1450℃保温30min,烧结体的相对密度达到95%,抗压强度为2105MPa,压缩率达到30.9%,接近铸态合金力学性能。烧结体在α＋γ相区和α相区保温1h,相对密度分别为73%和85%。在1300～1400℃,随着片层团的增加,烧结体组织由双态组织逐渐变为全片层组织。在超固相液相区,随着γ相的减少,烧结体组织由近片层组织逐渐转变为全片层组织。

TiAl alloy was prepared by an injection forming of gas atomized pre-alloy powders of Ti-47.5Al-2.5V-1.0Cr. The sintering processes and their effects of sintering processes on microstructure, density and compressive property of the alloy sintered were investigated. The results show that relative density of 73% and 85% of the sintered alloys were obtained at α＋γ two phases field and α phase field after 60 min holding respectively. The sintered alloy of a near full density of 95% was obtained by supersolidus sintering at 1450 ℃ holding 30 min and its compression strength and compression ratio were 2105 MPa and 30.9% respectively, which are near to that of the cast alloy. With lamellar increasing, the microstructure was changed from DP microstructure to FL microstructure when the sintering temperature changed from 1300 to 1400 ℃. With the amount of γ phase decreasing gradually, the microstructure was changed from almost a lamellar microstructure to a fully lamellar microstructure at supersolidus liquid phase field.