TC4钛合金/N4纯镍激光高熵化填粉焊接组织性能研究

Microstructure and Properties of TC4/N4 Laser Welded Joint with High-entropy Filler Powder

目的解决TC4/N4异种金属的焊接问题,拓展钛/镍异种金属复合结构的应用范围。方法选用Cu_(x)CoCrMnAl_(0.8)Si_(0.2)高熵填充粉末,采用激光填充粉末焊接的方式实现TC4钛合金和N4纯镍异种金属的连接,对焊缝的表面形貌、显微组织、相成分等微观特征进行表征,测试焊接接头的显微硬度和拉伸性能。结果激光高熵化填粉焊接接头成形良好,无明显缺陷。通过微观组织表征发现,近钛侧存在以β-Ti+Ti_(2)Ni共晶相为主、宽度为50μm的化合物区,焊缝内部由等轴枝晶、少量雪花状组织和富Cr的沉淀相组成。焊接接头强度远低于母材强度,焊缝硬度高于母材硬度,近钛侧焊缝区硬度高于近镍侧焊缝区硬度。结论激光高熵化填粉焊接可实现钛/镍异种金属的连接,改善高熵填充粉末成分,调控焊缝金属的微观结构与接头性能。

The work aims to solve the welding problem of TC4/N4 dissimilar metals,and expand the application range of Ti/Ni dissimilar metal composite structure.TC4 titanium alloy and N4 pure nickel were joined by laser welding with high-entropy filler powder Cu_(x)CoCrMnAl_(0.8)Si_(0.2).The weld appearance,microstructure and phase composition of joints were characterized and then the microhardness and tensile properties were tested.The joints welded by high-entropy filler powder were good without obvious defects.Through microstructure characterization,it was found that there was a compound zone with a thickness of 50μm,which was mainly composed of β-Ti+Ti_(2)Ni eutectic phase,and the inside of the weld was composed of equiaxed dendrites,a small amount of snowflake structure and Cr-rich precipitates.The strength of welding joints was much lower than that of base material.The hardness of weld was higher than that of base material,and the hardness of near-titanium weld was higher than that of near-nickel weld.Laser welding with high-entropy filler powder can realize the connection of Ti/Ni dissimilar metals,improve the composition of high-entropy filler powder,and regulate the microstructure and joint performance of weld metal.