电磁悬浮下Ti-Al-Zr合金的快速枝晶生长与腐蚀机理  

Rapid dendrite growth and corrosion mechanism of Ti-Al-Zr alloy by electromagnetic levitation processing

作　　者：肖瑞麟 孙崇昊 刘克伦 阮莹[1] XIAO Rui-lin;SUN Chong-hao;LIU Ke-lun;RUAN Ying(School of Physical Science and Technology,Northwestern Polytechnical University,Xi’an 710072,China)

机构地区：[1]西北工业大学物理科学与技术学院,西安710072

出　　处：《中国有色金属学报》2023年第12期4059-4069,共11页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(52225406,52073232,52088101,U1806219);国家重点研发计划资助项目(2021YFB3700801);陕西省杰出青年科学基金资助项目(2020JC-11);陕西省科技创新团队项目(2021TD-14)。

摘　　要：采用电磁悬浮技术实现Ti_(47)Al_(47)Zr_(6)合金的快速凝固,并结合电化学方法对合金在模拟海水条件下的耐腐蚀性能进行研究。结果表明:电磁悬浮条件下α-Ti枝晶生长速度随过冷度增大呈指数型增大;在277 K的过冷度下,α-Ti枝晶的生长速度达到15 m/s;随过冷度的增大,合金中初生α-Ti枝晶显著细化,枝晶间γ相的形成被抑制;枝晶间γ相耐腐蚀性能最差,点蚀先发生在枝晶间的γ相中,然后,腐蚀向α-Ti枝晶发生共析转变形成的板条状γ+α_(2)区域蔓延,并且从γ相到α_(2)相相继被腐蚀。提高枝晶间γ相中Zr含量能够强化钝化膜的保护性,阻碍枝晶间γ相点蚀的发生。而且,减少枝晶间γ相的晶粒数量可以削弱微电偶效应,降低合金的点蚀敏感性,从而其延缓腐蚀进程。Ti-Al based alloys are widely used as low pressure turbine blades,compressor blades and nozzles in aviation and aerospace industry owing to the low density,high strength,excellent oxidation resistance and anticreep performance.However,the corrosion mechanism and corrosion resistance of the rapid solidified alloys are not clear.In this work,the rapid solidification of Ti-Al-Zr alloy was realized by means of electromagnetic levitation (EML).The achieved maximum undercooling of Ti-Al-Zr alloy was 277 K.There existed an exponential relationship between the α-Ti dendrite growth velocity and undercooling.The achieved maximum dendrite growth velocity was 15 m/s at the undercooling of 277 K.The further analysis on corrosion morphology for rapid solidified Ti-Al-Zr alloy illustrated that the interdendritic γ phase had a worst corrosion resistance.The corrosion was firstly occurred in interdendritic γ phase,then γ phase in γ+α_(2) lath area,and finally α_(2) phase.The increasing of content of Zr in interdendritic γ phase can enhance the protection of the passive film to interdendritic γ phase and hinder the pit of the interdendritic γ phase.Moreover,the decreasing of the quantity of interdendritic γ grains weakened micro-galvanic effect and reduced pitting sensitivity,consequently delayed the corrosion process.Therefore,the corrosion resistance of Ti-Al-Zr alloy can be controlled effectively by controlling of the solute trapping effect and the alloy's microstructure through rapid solidification.

关 键 词：钛合金 电磁悬浮 快速晶体生长 腐蚀机理 

分 类 号：TG146.2[一般工业技术—材料科学与工程]