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Mo、Zr 元素对新型α+β钛合金显微组织与 力学性能影响研究
Effect of Mo and Zr Addition on the Microstructure and Mechanical Properties of a Novel α+β Titanium Alloy
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- DOI:
- 作者:
- 韩易恒1，陈文韬1，戴锦华1，吴嘉琪1，梅金娜2，唐 斌1，3
HANYiheng1, CHEN Wentao1, DAI Jinhua1, WU Jiaqi1, MEI Jinna2, TANG Bin1,3
- 作者单位:
- 1. 西北工业大学凝固技术全国重点实验室，陕西西安710072；2.苏州热工研究院有限公司，江苏苏州215002；3.西北 工业大学重庆科创中心，重庆401135
1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China; 2. Suzhou Nuclear Power Research Institute Co., Ltd., Suzhou 215002, China; 3. Innovation Center NPU Chongqing, Chongqing 401135, China
- 关键词:
- Ti575；Mo 含量；Zr 含量；强塑性匹配
Ti575; Mo content; Zr content; strength and plasticity
- 摘要:
- 研究了Mo、Zr元素对新型α+β钛合金Ti575显微组织与力学性能的影响。通过真空电弧熔炼获得具 有不同Mo、Zr 含量的Ti575 合金：Ti-5Al-7.5V-0.5Si(Ti575)，Ti-5Al-7.5V-1Mo-0.5Si(1Mo)，Ti-5Al-7.5V-1Zr-0.5Si(1Zr)， Ti-5Al-7.5V-0.5Mo-0.5Zr-0.5Si (0.5Mo-0.5Zr)。 对 4 种合金进行 940 ℃/1 h 单相区固溶与 550 ℃/6 h 两相区时效处理，并 进行拉伸性能试验与组织表征。 结果表明，随Mo含量增加，Ti575合金片层α与次生α尺寸显著细化；Zr对α相细化 作用弱于Mo， 但降低硅化物形核能， 在Ti575-1Zr合金中观察到大量硅化物析出， 其他成分合金则未观察到。 对于 Ti575-1Mo 合金，Mo 元素起固溶强化作用，同时片层α细化与次生α细化显著缩短位错滑移平均自由程，因而其抗拉 强度(UTS)较 Ti575 合金大幅提升同时伸长率(εf )有所损失(UTS：Ti575：956 MPa，1Mo：1 046 MPa；εf：Ti575：13.6%， 1Mo：9.4%)。 对于 Ti575-1Zr 合金，相较 Ti575 合金其片层 α 与次生 α未显著细化，其强度提升归因于Zr元素固溶强化 与硅化物析出强化，然而硅化物与基体间应变失配促进孔洞形核，降低伸长率(UTS：Ti575：956MPa，1Zr：995MPa；εf： Ti575：13.6%， 1Zr：10.8%)。 对于 0.5Mo-0.5Zr 合金，一方面 0.5%(质量分数)Mo 元素在细化 α 片层同时不会使其过于细 小， 另一方面0.5%Zr 元素起固溶强化作用同时避免界面硅化物过度析出。 综合作用下，0.5Mo-0.5Zr合金相较 Ti575 合金强度大幅提升同时塑性损失较小，具备最佳强塑匹配(UTS:Ti575:956MPa，0.5Mo-0.5Zr:1 053 MPa；εf : Ti575: 13.6%，0.5Mo-0.5Zr: 11.8%) 。
The effects of Mo and Zr on the microstructure and mechanical properties of a novel α+β titanium alloy, Ti575, were investigated. Ti575 alloys with different contents of Mo and Zr, including Ti-5Al-7.5V-0.5Si (Ti575), Ti-5Al 7.5V-1Mo-0.5Si (1Mo), Ti-5Al-7.5V-1Zr-0.5Si (1Zr), and Ti-5Al-7.5V-0.5Mo-0.5Zr-0.5Si (0.5Mo-0.5Zr), were obtained via vacuum arc melting. The four alloys were treated with β single-phase region solution at 940 ℃ for 1 h, followed by two-phase aging at 550 ℃ for 6 h, and then subjected to tensile testing and microstructure characterization. The experimental results show that with increasing Mo content, the lamellar α and secondary α sizes of the Ti575 alloy significantly decrease. The refining effect of Zr on the α phase is weaker than that of Mo. Zr addition reduces the nucleation energy of silicide. Many silicide precipitates are observed in the Ti575-1Zr alloy, whereas no significant silicide is observed in the Ti575, 1Mo and 1Zr alloys. For the Ti575-1Mo alloy, Mo has a significant solid solution strengthening effect, and the α refinement of the lamellae and secondary microstructure significantly shorten the mean free path of dislocation slip. Therefore, the tensile strength (UTS) of the alloy is significantly greater than that of the Ti575 alloy, while the elongation (εf ) decreases accordingly (UTS: Ti575:956 MPa, 1Mo: 1 046 MPa; εf : Ti575: 13.6%, 1Mo: 9.4%). For the Ti575-1Zr alloy, the lamellar α and secondary α are not significantly refined compared with those of the Ti575 alloy, and the strength improvement is attributed to the solid solution strengthening of Zr and the silicide precipitation strengthening. However, the strain mismatch between the silicide and the matrix promotes pore nucleation and decreases the rate of elongation (UTS: Ti575; 956 MPa, 1Zr: 995 MPa; εf : Ti575; 13.6%, 1Zr: 10.8%). For the 0.5Mo-0.5Zr alloy, on the one hand, 0.5 wt.% Mo can refine the α lamellar structure without making it too tiny. On the other hand, 0.5 wt.% Zr not only plays a role in solid solution strengthening but also avoids excessive precipitation of interfacial silicides.Compared with that of the Ti575 alloy, the strength of the 0.5Mo-0.5Zr alloy is greatly improved under the combined action of Mo and Zr, while its plastic loss is insignificant, leading to the best strength-ductility synergy(UTS: Ti575: 956 MPa, 0.5Mo-0.5Zr: 1 053 MPa; εf : Ti575: 13.6%, 0.5Mo-0.5Zr: 11.8%).