Effect of zirconium content on the microstructure and corrosion behavior of as-cast Ti-Al-Nb-Zr-Mo alloy
Effect of zirconium content on the microstructure and corrosion behavior of as-cast Ti-Al-Nb-Zr-Mo alloy
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DOI：
10.1016/j.jmrt.2021.10.102
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发表时间：
2021-10
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影响因子：
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通讯作者：
Baoxian Su;Binbin Wang;L. Luo;Liang Wang;Yan-Qing Su;Yan-Jin Xu;Fuxin Wang;Baoshuai Han
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文献类型：
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作者：
Baoxian Su;Binbin Wang;L. Luo;Liang Wang;Yan-Qing Su;Yan-Jin Xu;Fuxin Wang;Baoshuai Han
研究如何提高钛合金的腐蚀性能对其在腐蚀环境中的实际应用具有重要意义。本文采用显微组织表征、电化学测试和失重测试等手段，系统地研究了不同含锆量对Ti-6Al-3Nb-xZr-1Mo(x=0.2，6，10，20和40wt%)合金腐蚀行为的影响。结果表明，所研究的合金均由α和β相组成，但随着Zr含量的增加，合金中片层状α相的厚度细化，晶间残留β相的体积分数增加。同时，随着含锆量的增加，合金的耐蚀性单调提高，直接表现为腐蚀电流密度降低，极化电阻提高，腐蚀速率降低。腐蚀性能的改善是由于α和β相之间形成的微电偶腐蚀减轻，耐蚀β相体积分数的增加和氧化膜成分的改变所致。值得注意的是，当Zr加入量达到40wt%时，腐蚀模式由均匀腐蚀转变为混合点蚀和均匀腐蚀。此外，浸泡试验后的表面分析表明，片状α相比相邻的晶间β相更容易腐蚀，这是由于其钛和铝元素含量较高所致。目前的研究结果为通过成分优化设计海洋、生物医学和盐酸工业的高耐蚀性材料提供了参考数据。
Investigation about how to enhance the corrosion properties of Ti alloys is essential to their actual applications in corrosive environments. Herein, the specific influences of Zr content on the corrosion behavior of Ti-6Al-3Nb-xZr-1Mo alloys (x= 2, 6, 10, 20 and 40 wt%) are systematically investigated using microstructure characterization, electrochemical and weight loss measurements. The results signify that all investigated alloys are composed of α and β phases; however, the increase of Zr content endows alloys with the refined thickness of lamellar α phase and enhanced volume fraction of intergranular retained β phase. Meanwhile, the corrosion resistance monotonously improves along with increasing the Zr content, directly characterized by the decreased corrosion current density, improved polarization resistance as well as reduced corrosion rate. The improvement in corrosion performance is a result of the alleviated micro-galvanic corrosion formed between α and β phases, increased volume fraction of corrosion-resistant β phase and modified composition of oxide film. One should note that the corrosion mode changes from the uniform corrosion to the mixed pitting and uniform corrosion with the Zr addition up to 40 wt%. Besides, surface analysis of samples after immersion tests reveals that the lamellar α phase is more susceptible to corrosion compared to the adjacent intergranular β phase, attributed to its higher concentration of Ti and Al elements. The current findings provide data that can be referenced for designing high-corrosion resistance materials for marine, biomedical applications and hydrochloric acid industries through composition optimization.