Microstructure and mechanical properties of Cu-based bulk amorphous alloy billets fabricated by spark plasma sintering

In this study, Cu-based bulk amorphous alloy billets were fabricated by a powder metallurgy route, and their microstructure and mechanical properties were investigated. Rapidly solidified amorphous powders were produced by a conventional N₂ gas atomization method. In order to consolidate amorphous alloy billets, a spark plasma sintering (SPS) equipment was set up, and variables for hot consolidation were established. Using the consolidation temperature of 480 °C under a pressure of 80 MPa, good quality amorphous alloy billets having very few micropores or crystalline phase particles were obtained. Compressive strength of the billet was 1.8 GPa, which was about 6% lower than that of the cast amorphous alloy billet. This reduction was associated with the presence of few micropores, crystalline phase particles and thin oxide layers formed along prior powder boundaries in the billets. Amorphous matrix composite billets containing Cu particles homogeneously distributed in the amorphous matrix were successfully fabricated by the SPS consolidation. These composite billets showed a considerable amount of plastic strain because of the presence of ductile Cu particles, although their compressive strength was lower than that of the amorphous alloy billets.