时效温度对Ti-5Al-4Zr-10Mo-3Cr钛合金微观组织及力学性能的影响

研究了Ti-5Al-4Zr-10Mo-3Cr合金经过β相区固溶(880 ℃)、不同温度时效(540~620 ℃)处理后次生α相(α_s)析出形貌及其对力学性能的影响。结果表明:随着时效温度由540 ℃升高至620 ℃,合金中析出α_s相片层厚度由0.030 μm增加到0.142 μm,屈服强度由1353 MPa降低至1074 MPa,断后伸长率由2.5%升高至11.4%,即时效析出的微米级片层α_s能够显著调控合金的力学性能。此外,时效温度升高使合金的拉伸断裂由沿晶脆性断裂为主转变为韧窝穿晶为主的韧性断裂方式。Ti-5Al-4Zr-10Mo-3Cr合金时效析出的片层状α_s相的厚度大于0.1 μm,合金的断后伸长率≥6%。当时效温度为600 ℃时,合金的硬度为387 HV10,抗拉强度为1182 MPa,伸长率为8.5%,具有良好的强塑性匹配。

Effect of aging temperature on microstructure and mechanical properties of Ti-5Al-4Zr-10Mo-3Cr titanium alloy

Precipitation behavior and mechanical properties of secondary α phase (α_s) in the Ti-5Al-4Zr-10Mo-3Cr alloy after solution treatment in β phase region (at 880 ℃) and aging at different temperatures (540-620 ℃) were studied. The results show that with the aging temperature increasing from 540 ℃ to 620 ℃, the thickness of precipitated α_s increases from 0.030 μm to 0.142 μm, the yield strength decreases from 1353 MPa to 1074 MPa, and the elongation after fracture increases from 2.5% to 11.4%. This indicates that the micro-scaled α_s precipitated by aging can regulate the mechanical properties of the alloy. In addition, with the increase of aging temperature, the tensile fracture of the alloy changes from intergranular brittle fracture to dimple transgranular ductile fracture. The thickness of the α precipitation in the Ti-5Al-4Zr-10Mo-3Cr alloy is greater than 0.1 μm, which brings about the elongation after fracture larger than 6%. When the aging temperature is 600 ℃, the hardness, tensile strength and elongation after fracture are 387 HV10, 1182 MPa and 8.5% respectively, possessing good combination of strength and ductility.