后处理对激光沉积制造γ-TiAl合金组织与性能的影响

Effects of post treatment on microstructure and properties of γ-TiAl alloy fabricated by laser deposition manufacturing

通过固溶、热等静压+固溶处理对激光沉积制造(LDM)Ti4822合金进行组织结构调整和相比例控制,分析不同激光沉积制造后处理工艺对合金组织和性能的影响。结果表明,经固溶、热等静压+固溶处理两种处理后γ-TiAl合金组织均含有γ、α_2及微量B2相;1260℃热处理后γ-TiAl合金形成典型的双态组织;1330℃热处理后γ-TiAl合金形成近片层组织;1350℃热处理后γ-TiAl合金形成全片层组织;热等静压导致组织内的层片尺寸略有增大。随热处理温度的升高γ-TiAl合金显微硬度逐渐减小,在相同热处理温度下,经热等静压处理后的样品显微硬度提高约5%,热等静压导致合金组织致密度提升的强化效果要高于片层组织粗化引起的弱化效果。

Solution and hot isostatic pressing（ HIP） plus solution treatments were carried out to adjust the as-deposited microstructure and phase constitution of the γ-TiAl（ Ti-48Al-2Cr-2Nb,Ti4822） block samples fabricated by laser deposition manufacturing（ LDM）,and the effect of post treatment on mechanical properties of the alloy was studied. The results show that the structure of the γ-TiAl alloy contains γphase,α2 phase and trace B2 phase after solid solution or hot isostatic pressing plus solution treatment. The duplex microstructure,nearlamellar microstructure and full-lamellar microstructure of the alloy are obtained after solution treatment at 1260 ℃,1330 ℃ and 1350℃,respectively. The lamellar size within the microstructure increases slightly by hot isostatic pressing treatment. The micro-hardness of the alloy decreases gradually with the increasing of the solution temperature,and the micro-hardness of the alloy treated by HIP is 5% higher than that of by solution treatment at the same temperature. The strengthening effect caused by increasing of microstructure density of the alloy after HIP treatment is higher than the weaken effect caused by coarsening of lamellar microstructure.