Cite this article as:

Xiaozhao Ma, Zhilei Xiang, Tao Li, Yilan Chen, Yingying Liu, Ziyong Chen, and Qun Shu, Evolution laws of microstructures and mechanical properties during heat treatments for near-α high-temperature titanium alloys, Int. J. Miner. Metall. Mater., 29(2022), No. 8, pp.1596-1607. https://dx.doi.org/10.1007/s12613-021-2248-8
Xiaozhao Ma, Zhilei Xiang, Tao Li, Yilan Chen, Yingying Liu, Ziyong Chen, and Qun Shu, Evolution laws of microstructures and mechanical properties during heat treatments for near-α high-temperature titanium alloys, Int. J. Miner. Metall. Mater., 29(2022), No. 8, pp.1596-1607. https://dx.doi.org/10.1007/s12613-021-2248-8
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近 α 耐高温钛合金的显微组织和力学性能在热处理过程中的演变规律

摘要: 耐高温钛合金具有比强度高、比模量高和高温性能优异的优点,主要应用在高性能航空发动机叶片和叶盘,超声速巡航导弹壳体和军用柴油发动机气门等领域。然而,目前对新型耐650℃高温钛合金热处理过程中微纳结构和力学性能演变的研究尚少。本文通过XRD、SEM、EBSD、TEM和拉伸试验等方法研究了热处理过程中合金的显微组织、力学性能和断裂特征的演变规律。研究表明,随固溶温度提升,初生 α 相含量逐渐较小,β 转变组织含量逐渐增加。β 转变组织内部析出大量层片状 α 晶粒, 层片的宽度随固溶温度的提升逐渐增加。锻态合金内部既存在尺寸较大的等轴和棒状硅化物,也析出纳米尺寸的硅化物。元素分析表明,大尺寸硅化物或许为(Ti, Zr, Nb)5Si3 和 (Ti, Zr, Nb)6Si3。热处理后,尺寸较小的棒状硅化物在残余 β 相中析出,它们与 α/β 界面近似为45°。热处理态合金中的残余 β 相呈半连续状。合金经980°C/1 h固溶和700°C/4 h时效处理后表现出最优的室温和高温(650°C)力学性能的匹配。

 

Evolution laws of microstructures and mechanical properties during heat treatments for near-α high-temperature titanium alloys

Abstract: Evolution laws of microstructures, mechanical properties, and fractographs after different solution temperatures were investigated through various analysis methods. With the increasing solution temperatures, contents of the primary α phase decreased, and contents of transformed β structures increased. Lamellar α grains dominated the characteristics of transformed β structures, and widths of secondary α lamellas increased monotonously. For as-forged alloy, large silicides with equiaxed and rod-like morphologies, and nano-scale silicides were found. Silicides with large sizes might be (Ti, Zr, Nb)5Si3 and (Ti, Zr, Nb)6Si3. Rod-like silicides with small sizes precipitated in retained β phase, exhibiting near 45° angles with α/β boundaries. Retained β phases in as-heat treated alloys were incontinuous. 980STA exhibited an excellent combination of room temperature (RT) and 650°C mechanical properties. Characteristics of fracture surfaces largely depended on the evolutions of microstructures. Meanwhile, silicides promoted the formation of mico-voids.

 

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