激光熔化沉积连接钛-铝异质合金工艺及组织性能研究

Study on the process and microstructure properties of titanium-aluminum heteroalloy connected by laser melting deposition

摘要:

目的 解决物性参数差异大的TC4-7075异质合金的连接难题，拓展高比强度钛-铝异质合金复合结构的应用范围。方法 选用AlTiVNbSi高熵合金为中间层材料，采用激光熔化沉积技术实现了TC4和AA7075异质合金的有效连接，采用金相显微镜（OM）、扫描电子显微镜（SEM、EBSD）、显微硬度以及拉伸实验等检测方法，对连接区的宏观形貌、微观组织、成分分布以及界面特性等微观特征进行了表征。结果 连接接头与TC4钛合金侧界面结合良好，存在宽度约为20μm的界面过渡区，靠近界面的TC4有集束魏氏组织产生，7075侧界面存在宽度为20μm的化合物区。结论 基于高熵合金的以AlTiVNbSi为中间层材料，采用激光熔化沉积技术可实现钛-铝异质合金的有效连接，连接接头硬度约为696HV，高于母材硬度，近钛侧连接区硬度高于近铝侧连接区硬度，抗拉强度为116MPa。

Abstract:

Objective To solve the connection problem of TC4-7075 heteroalloy with large differences in physical parameters, and to expand the application range of high specific strength titanium-aluminum heteroalloy composite structure. Methods AlTiVNbSi high-entropy alloy was selected as the intermediate layer material, and the effective connection of TC4 and AA7075 heteroalloys was realized by laser melting deposition technology, and the macromorphology, microstructure, component distribution and interface characteristics of the junction area were characterized by metallographic microscopy (OM), scanning electron microscopy (SEM, EBSD), microhardness and tensile experiment. Results The connection joint is well combined with the TC4 titanium alloy side interface, and there is an interface transition zone with a width of about 20μm, TC4 near the interface has bundled Weisler tissue, and a compound area with a width of 20μm exists at the 7075 side interface. Conclusion Based on AlTiVNbSi as the intermediate layer material of high-entropy alloy, laser melting deposition technology can realize the effective connection of titanium-aluminum heteroalloy, the hardness of the joint is about 696HV, which is higher than the hardness of the base metal, the hardness of the connecting zone on the near titanium side is higher than that of the connecting zone on the aluminum side, and the tensile strength is 116MPa.