Brazing of Cu with Pd-based metallic glass filler

Metallic glass has several unique properties, including high mechanical strength, small solidification shrinkage, small elastic modulus and supercooling state, all of which are well suited as a residual stress buffer for metal and ceramic joining. In the present preliminary study, we demonstrated brazing of Cu rods with Pd40Cu30Ni10P20 metallic glass filler. The brazing was carried out at 873 K for 1 min in a vacuum atmosphere (1 × 10−3 Pa), and then the specimens were quenched at the rate of 30 K/s by blowing He. The metallic glass brazing of Cu using Pd40Cu30Ni10P20 filler was successful, with the exception that several voids remained in the filler. According to micro-focused X-ray diffraction, no diffraction patterns were observed at both the center of the Pd40Cu30Ni10P20 filler and the Cu/Pd40Cu30Ni10P20 interface. The result showed that the Cu specimens were joined with Pd40Cu30Ni10P20 filler in the glassy state. The tensile fracture strength of the brazed specimens ranged from 20 to 250 MPa. The crack extension from the voids in the Pd40Cu30Ni10P20 filler may have caused the results to be uneven and very low compared to the strength of Pd-based bulk metallic glass.