双时效对Ti-4Al-5Mo-6Cr-5V-1Nb合金显微组织和力学性能的影响

Effect of Duplex Aging on Microstructure and Mechanical Property of Ti-4Al-5Mo-6Cr-5V-1Nb alloy

摘要:

研究了固溶、固溶后单时效以及固溶后双时效处理对Ti-4Al-5Mo-6Cr-5V-1Nb合金组织和力学性能的影响。结果表明，820 ℃下固溶0.5 h后，合金中的α相完全溶解；单/双时效合金的硬度均随时效时间增加先升高后降低；合金经300 ℃/8 h+500 ℃/8 h双时效处理后可达到458 HV的峰值硬度，1462 MPa抗拉强度以及3.4%延伸率，其强度比原始合金高6%，也高于单时效合金。界面能计算结果表明ω相使α相形核的阻力降低50%，促进了α相的析出并细化α板条，从而提升合金的硬度，强度及塑性。

Abstract:

Effects of solution treatment, single aging treatment, and duplex aging treatment on the microstructure and mechanical property of Ti-4Al-5Mo-6Cr-5V-1Nb alloy are studied. After the solution treatment at 820 ℃ for 0.5 h, α phase completely dissolved. The hardness of single/ duplex aging treated alloys both increase at the beginning and then decrease. The alloy duplex aging treated at 300 ℃ for 8 h and 500 ℃ for 8 h processes the peak-aging hardness of 458 HV, ultimate tensile strength (UTS) of 1462 MPa and elongation of 3.4%, whose UTS is 6% higher than original alloy and even higher than single aging treated alloy. The calculation of interface energy indicates that ω phase can promote the precipitation of α phase and the refinement of α lath by decreasing the nucleation resistance of α phase by 50%, thus increasing the hardness, strength, and elongation of alloys.