The key to high-quality metallic glass casting: Interfacial reaction associated with vacuum induction melting process procedures

Abstract

Even though vacuum induction melting (VIM) is widely employed in the industrial production of bulk metallic glasses (BMGs), the effect and mechanism of the interfacial reaction between the melt and the oxide ceramic crucible on BMG formations are not yet fully understood. Here, the influences and mechanisms of the interfacial reaction on a Zr-based BMG (Vit 105) subjected to various melting temperatures and holding times are revealed by employing experiments and theoretical calculations. We find that the degree of interfacial reaction is intriguingly correlated with the process parameters during VIM processing, leading to an increase in the oxygen content of the alloy and the reaction layer thickness. Besides, the increase of oxygen content also induces variations in the ordering and shear transformation zone (STZ) size of the BMGs, thus resulting in the precipitation of a nanoscale fcc phase and affecting the mechanical properties and reliability under deformation of the alloy. Furthermore, thermodynamic and kinetic parameters involved in the interfacial reaction, such as the molar Gibbs free energy of each element, the apparent activation energy, etc., are obtained, providing a comprehensive understanding of the transport processes at play. Our findings provide new insights into the preparation of BMGs by VIM and may be expanded to other melting techniques to accelerate the commercial application of metallic glasses.