Since the discovery of 18K gold bulk metallic glass in 2004, many efforts have been put into understanding the physical properties as well as the processing pathways of metallic glass. Currently, a few commercial products that utilize metallic glass are available on the market, and almost all of them rely on casting technology. In this paper we present an alternative technique to process 18K gold bulk metallic glass to realize the full potential of these amorphous alloys. By mimicking the thermoforming process of plastics, our lab developed a wide range of processing methods to use the softening behavior of bulk metallic glass in the super-cooled liquid temperature range between glass transition and crystallization temperatures. The Au49Ag5.5Pd2.3Cu26.9Si16.3 gold alloy was fabricated in the form of granules as feedstock to be used in subsequent thermoforming processes. Two processes were chosen for comparative study: conventional compression forming and electrical resistance heat forming. Our investigation included porosity measurements, hardness profile, reaction layer study, viscosity, crystallization behavior and crystallography, corrosion and tarnish resistance as well as size distribution as related to granulation pressure, nozzle size, and granulation temperature.

Author(s): Chaiyapat Tangpatjaroen