Fabrication of Bulk Metallic Glass Composites at Low Processing Temperatures

Abstract

Bulk metallic glasses (BMGs) are amorphous alloys that exhibit unique mechanical properties such as high strength due to their liquid-like structure in the vitreous solid state. While they usually exhibit low ductility, they can be toughened by incorporating secondary phase particles within the amorphous matrix via composite fabrication to generate amorphous metal matrix composites (MMCs). Traditional MMCs are fabricated at high temperature in the liquid state with tedious blending processes. This high temperature processing route often leads to unwanted reactions at the reinforcement/matrix interface, creating brittle intermetallic by-products and damaging the reinforcement. In the present work, novel bulk metallic glass composites (BMGCs) were fabricated at low processing temperatures via thermoplastic forming (TPF) above the glass transition temperature of the amorphous matrix. Here, the unique thermophysical features of the matrix material allow for TPF of composites in non-sacrificial moulds incorporating various types of reinforcement, via processing in the solid state at low temperatures (less than 200 °C), within a short timeframe (less than 10 minutes); this avoids the formation of brittle phases at the reinforcement/matrix interface leading to efficient bonding between particles and matrix, thereby creating a tough, low density composite material.