Brazing of TC4 Alloy Using Ti-Zr-Ni-Cu-Sn Amorphous Braze Fillers

Area of Science:

• Materials Science
• Metallurgy
• Joining Technology

Background:

• Excessive brittle intermetallic compounds (IMC) formation is a critical issue in TC4 brazed joints.
• Amorphous braze fillers offer potential solutions for improving joint properties.

Purpose of the Study:

• To design and evaluate novel Ti-Zr-Cu-Ni-Sn amorphous braze fillers for TC4 joints.
• To investigate the effect of filler composition on microstructure and shear strength.
• To address the problem of brittle IMC formation in TC4 brazed joints.

Main Methods:

• Design of two Ti-Zr-Cu-Ni-Sn amorphous braze fillers.
• Microstructural analysis using SEM, TEM, and XRD.
• Shear strength testing at room and elevated temperatures.
• Evaluation of TC4/braze filler/TC4 joints.

Main Results:

• The optimized Ti35Zr25Ni15Cu20Sn5 filler, closer to the eutectic point, exhibited a lower melting point.
• This optimized filler facilitated better diffusion and reduced residual (Ti,Zr)2(Ni,Cu) content.
• Maximum room-temperature shear strength reached 472 MPa and high-temperature strength reached 389 MPa at 970 °C/10 min.
• These strengths were 66% and 48% higher, respectively, than those achieved with the equiatomic filler.

Conclusions:

• The near-eutectic Ti35Zr25Ni15Cu20Sn5 amorphous braze filler effectively improves the shear strength of TC4 brazed joints.
• Reduced IMC formation and enhanced element diffusion contribute to superior joint performance.
• The developed fillers offer a promising approach for high-performance TC4 joining applications.