Optimization of the Microstructure and Mechanical Properties of a TC4 Alloy Joint Brazed with a Zr-Based Filler Containing a Co Element
Zhan Sun,
Deshui Yu,
Lixia Zhang,
Mingjia Sun,
Boyu Zhang,
Weimin Long,
Sujuan Zhong
Affiliations
Zhan Sun
State Key Laboratory of Precision Welding & Joining of Materials and Structures, Harbin 150001, China
Deshui Yu
State Key Laboratory of Precision Welding & Joining of Materials and Structures, Harbin 150001, China
Lixia Zhang
State Key Laboratory of Precision Welding & Joining of Materials and Structures, Harbin 150001, China
Mingjia Sun
State Key Laboratory of Precision Welding & Joining of Materials and Structures, Harbin 150001, China
Boyu Zhang
State Key Laboratory of Precision Welding & Joining of Materials and Structures, Harbin 150001, China
Weimin Long
State Key Laboratory of Advanced Brazing Filler Metals & Technology, Zhengzhou Research Institute of Mechanical Engineering Co., Ltd., Zhengzhou 450001, China
Sujuan Zhong
State Key Laboratory of Advanced Brazing Filler Metals & Technology, Zhengzhou Research Institute of Mechanical Engineering Co., Ltd., Zhengzhou 450001, China
Herein, we fabricated a low-melting-point Zr-16Ti-6Cu-8Ni-6Co eutectic filler based on a Zr-Ti-Cu-Ni filler to achieve effective joining of a Ti6Al4V (TC4) titanium alloy. The temperature at which the brittle intermetallic compound (IMC) layer in the seam completely disappeared was reduced from 920 °C to 900 °C, which broadened the temperature range of the Zr-based filler, brazing the TC4 without a brittle IMC layer. The shear strength of the Zr-16Ti-6Cu-8Ni-6Co brazed joint increased by 113% more than that of the Zr-16Ti-9Cu-11Ni brazed joint at 900 °C. The proportion of β-Ti in the seam of the Zr-16Ti-6Cu-8Ni-6Co brazed joint increased by 21.31% compared with that of the Zr-16Ti-9Cu-11Ni brazed joint. The nano-indentation results show that the elastic modulus of the β-Ti (143 GPa) in the interface is lower than that of the α-Ti (169 GPa) and (Ti,Zr)2(Ni,Cu,Co) (203 GPa). As a result, the β-Ti is subjected to a greater strain under the same stress state compared with the α-Ti and (Ti,Zr)2(Ni,Cu,Co), and the Zr-16Ti-6Cu-8Ni-6Co brazed joint can maintain a higher strength than the Zr-16Ti-9Cu-11Ni brazed joint under a middle–low erosion area of the TC4 base metal. This provides valuable insights into the use of high-strength, fatigue-resistant TC4 brazed joints in engineering applications.
