扫描速度对钛合金NiCoCrAlY熔覆涂层显微组织及硬度的影响  

Microstructure and Hardness of NiCoCrAlY Coatings on Titanium Alloy by Laser Cladding with Different Scanning Speeds

作　　者：许瑞华[1,2] 黎向锋[1,2] 左敦稳[1] 王宏宇[3] 江世好[1] 李建忠[1] 

机构地区：[1]南京航空航天大学机电学院,江苏南京210016 [2]江苏省精密与微细制造技术重点实验室,江苏南京210016 [3]江苏大学机械工程学院,江苏镇江212013

出　　处：《稀有金属》2014年第5期807-812,共6页Chinese Journal of Rare Metals

基　　金：国家航空科学基金项目(2010ZE52056);江苏省精密与微细制造技术重点实验室基金;江苏省自然科学基金项目(BK2011479)资助

摘　　要：利用激光熔覆技术在Ti6A14V钛合金基体上制备NiCoCrAlY高温防护涂层,提高钛合金基体的高温性能。采用激光功率1.2 kW,光斑直径1 mm,研究激光扫描速度对Ti6A14V钛合金熔覆涂层宏观形貌、稀释率、截面组织以及硬度的影响。研究表明,在相同激光功率和激光光斑直径的条件下,熔覆层的宏观形貌在400 mm·min-1时质量最优,熔覆层表面连续且平整,波浪起伏较小;随着扫描速度增加,激光能量减小,熔覆层的几何尺寸以及稀释率均逐渐减小,当扫描速度为500mm·min-1时,熔化的液体中杂质仍未完全逸出就冷却凝固,涂层与基体之间出现微裂纹、气孔等缺陷;随着扫描速度的增加,温度梯度不断减小,冷却速度不断增大,初生的枝状晶不断被打破,熔覆层组织致密均匀,晶粒细小,同时熔覆层的硬度逐渐增大。To improve the high temperature resistance of Ti-6Al-4V substrate,the influence of scanning speed on surface morphology,dilution rate,microstructure of cross section and hardness of NiCoCrAlY coatings for high temperature protection on Ti6A14 V titanium alloy by laser cladding was investigated with the laser power of 1. 2 kW and the diameter of spot of 1 mm. The results showed that with scanning speed of 400 mm·min^-1,the macro-morphology of coating obtained the best quality under the same laser power and spot diameter,and the continuous and smooth coatings with small waves were obtained. With the laser scanning speed going up,both the geometry size and dilution rate of the coating reduced gradually. Defects such as microcrack and sinkhole appeared between coating and substrate due to that molten liquid was cooled and solidified before the inclusions were escaped with the scanning speed of 500mm·min^-1. With the scanning speed increasing,temperature gradient decreased and cooling speed increased. As the result,primary dendrite was broken and the microstructure of the coating became compact and uniform with small grain,which leaded to the increase of the hardness gradually.

关 键 词：激光熔覆 扫描速度 NICOCRALY涂层 显微组织 显微硬度 

分 类 号：TG174.4[金属学及工艺—金属表面处理]