Soldering Zr metallic glass to Ti alloy using pre-cladding ultrasonic processes

Abstract

That increasing temperature is beneficial for solder-wetting but not for amorphous-maintaining the state causes difficulties in joining of Zr-based bulk metallic glass (BMG). In order to solve the contradiction, this paper presents a two-step process of pre-cladding ultrasonic soldering, in which a Zn-6Al-3Cu-20Sn solder layer was firstly vacuum-cladded on surface of a Ti-6Al-4V sample, and then a Zr-14Cu-10Ti-8Ni BMG sample was ultrasonic-soldered to the solder layer without flux. Microstructures of the Zr-14Cu-10Ti-8Ni/Zn-6Al-3Cu-20Sn/Ti-6Al-4V soldering joints were studied using optical microscope, SEM, EDS, and XRD, and shear strengths were tested. Results show that shear strength ranges from 20 to 50 MPa among the joints obtained under different soldering temperatures and ultrasonic times. Shear fracture of all the experimental ultrasonic soldered joints occurred at the interface between solder and Zr-based BMG. The fracture surface shows a mixture of solder tearing and solder peeling off from the surface of the Zr-based BMG. Pits or grooves formed on surface of Zr-based BMG by ultrasonic cavitation benefit not only chemical adhesion but also mechanical adhesion by an anchoring effect. This work confirmed that ultrasonic treatment is very effective for the soldered joint of Zr-based BMG.