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| 高温氧化及时效处理对Ti-20Nb合金性能的影响研究 |
| Effects of High Temperature Oxidation and Aging Treatment on Properties of Ti-20Nb Alloy |
| Received:March 16, 2024 |
| DOI：10.3969/j.issn.1674-6457.2024.10.016 |
| 中文关键词: Ti-Nb合金 高温氧化 时效处理 微观组织 力学性能 |
| 英文关键词: Ti-Nb alloy high temperature oxidation aging treatment microstructure mechanical properties |
| 基金项目:国家自然科学基金(52171007) |
| Author Name | Affiliation | | XU Zhiyuan | School of Mechanical Engineering, Jiangnan University, Jiangsu Wuxi 214122, China | | CHEN Yulin | School of Mechanical Engineering, Jiangnan University, Jiangsu Wuxi 214122, China | | ZHANG Peng | School of Mechanical Engineering, Jiangnan University, Jiangsu Wuxi 214122, China | | ZHANG Jian | School of Mechanical Engineering, Jiangnan University, Jiangsu Wuxi 214122, China |
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| 中文摘要: |
| 目的 研究Ti-Nb二元亚稳β钛合金高温氧化及时效处理后合金的微观组织、相变特性以及力学性能，同时确定析出相与时效温度的对应关系，并分析析出相对合金性能的影响，为进一步提升Ti-Nb综合服役性能提供理论与工艺参考。方法 在β相单相区及双相区分别进行高温氧化与时效处理，结合OM、SEM以及TEM等手段分析热处理后的微观组织演变，采用DSC对热处理后的相变进行测试。在此基础上，在室温下进行拉伸性能测试并结合硬度测试综合分析合金的力学性能。结果 Ti-20Nb合金在单相区高温氧化1 h后从表面至中心形成了多层微观结构，包括TiO2及Nb2O5氧化物、α+β相以及α”相，并在升降温时相继发生了α”→β相变及β→iso-ω相变。继续对氧化后合金进行300、400、500 ℃的30 min时效处理，产生了弥散分布的iso-ω相以及α相的竞争析出，并抑制了α”→β相变以及β→iso-ω相变。同时发现在500 ℃时效30 min条件下力学性能提升效果最佳，实现了高强度(σb=953.6 MPa)和高断裂伸长率(δ=11%)，并获得了较低弹性模量(E=62.5 GPa)。结论 经过单相区高温氧化的Ti-20Nb合金具有复杂的多层结构特征，升温时仍可以发生多步相变。在高温氧化基础上进一步时效后，合金中主要析出相为iso-ω与α相，二者相互竞争析出，并共同抑制马氏体相变。同时大量iso-ω析出相易使合金发生脆断，同时提高其弹性模量，而α相可明显提升合金综合力学性能。 |
| 英文摘要: |
| The work aims to study the microstructure, phase transition behaviors and mechanical properties of Ti-Nb binary metastable β titanium alloy after high temperature oxidation and subsequent aging treatment and determine the relationship between precipitation and aging temperature, and analyze the effect of precipitation on alloy properties, so as to provide theoretical and technological references for further improving the comprehensive service performance of Ti-Nb. High temperature oxidation and aging treatment were carried out in β phase single-phase region and two-phase region respectively. Combined with OM, SEM and TEM, the microstructure evolution after heat treatment was analyzed and the DSC was used to characterize the phase transition behaviors after heat treatment. On this basis, the tensile test at room temperature combined with hardness test was carried out to comprehensively analyze the mechanical properties of the treated alloy. Ti-20Nb alloy was oxidized at high temperature for 1 h in single-phase region, and a multi-layer microstructure was formed from surface to center, consisting of TiO2 and Nb2O5 oxides, α+β phase and α phase, and α"→β and β→iso-ω phase transformation occurred successively during the heating. Then, the oxidized alloy was further aged at 300 ℃, 400 ℃ and 500 ℃ for 30 min, resulting in the competitive precipitation of dispersed iso-ω and α phases, and inhibiting α"→β martensitic transformation and β→iso-ω phase transition. Meanwhile, it was found that aging at 500 ℃ for 30 min had the best effect on improving mechanical properties. High strength (σb=953.6 MPa), high fracture elongation (δ=11%) and low elastic modulus (E=62.5 GPa) were obtained. The Ti-20Nb alloy, which has been oxidized at high temperature in the single-phase region, has complex multi-layer microstructure and various phase transitions with the increase of temperature. After further aging treatment of the oxidized samples, the precipitations are iso-ω and α phases, which compete with each other and jointly inhibit martensitic transformation. At the same time, a large number of iso-ω phases can easily make the alloy brittle and increase the elastic modulus, while the α phase can significantly improve the comprehensive mechanical properties of the alloy. |
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