γ-TiAl合金钎焊用钎料设计及接头组织研究

Research on Filler Design and Interface Microstructure for Brazingγ-TiAl Alloys

γ-TiAl合金是一种极具应用潜力的金属间化合物材料,采用所设计的Ti-15.6Zr-11.0Cu-9.8Ni(质量分数,%)钎料对其进行钎焊,分析接头组织形貌及元素分布,测试接头微区的显微硬度及接头强度,得出Al元素向界面发生扩散成为界面形成的主要驱动力;钎料元素Zr、Cu和Ni主要集中在近邻界面中心的部位。归因于晶粒组织粗大及硬度较高的网格状组织,钎焊断裂发生在界面中心部位。尽管界面靠近基体一侧出现了连续的Ti3Al相,但其塑性较好且硬度适中,因此有利于基体与界面之间力的传递和接头韧性。对接接头抗拉强度在室温下达到517 MPa,强度系数0.816。

γ–TiAl alloy is a kind of intermetallic compound material with great application potential.It was brazed by the designed filler as Ti–15.6Zr–11.0Cu–9.8Ni(mass fraction,%).The microstructure and element distribution of the joint were analyzed.The microhardness and strength of the joint were tested.It was found that the diffusion of Al to the interface was the main driving force for the formation of the interface.The Zr,Cu and Ni elements in the filler metal are mainly concentrated in the center of the adjacent interface.Due to the coarse grain structure and the high hardness of the grid structure,brazing fracture happened in the central part of the adjacent interface.Although there is a continuous Ti3Al phase near the interface,its excellent plasticity and the moderate hardness were beneficial to transfer the force between the matrix and the interface.Thus this phase was benefit for the toughness of the joint.The tensile strength of joint reaches to 517 MPa at room temperature,and the strength coefficient is 0.816。