Mechanical properties and thermal stability of thin film metallic glass compared to bulk metallic glass from ambient to elevated temperatures

Abstract

Metallic glasses can exhibit a wide range of local atomic arrangements which are determined by their processing history, and which control their mechanical properties. While recent studies show that thermally stable thin film metallic glasses with high strength and plasticity can be synthesized using physical vapor deposition, they often differ in terms of their structure and mechanical performance from bulk metallic glasses. In that aspect, two different fabrication methods – physical vapor deposition and arc melting – were utilized to fabricate compositionally similar Zr-based glasses in thin-film and bulk form. The as-fabricated samples were characterized in terms of oxygen concentration, element composition, and atomic structure. The mechanical response of the thin film metallic glass (TFMG) and the bulk metallic glass (BMG) was examined using in situ micropillar compression in a scanning electron microscope over a temperature range of room temperature to 500 °C. While the two glasses show overall similar failure characteristics, the TFMG exhibits higher strength together than the BMG without sacrificing plasticity at all testing temperatures. At elevated temperatures, the deformation mechanism changes to homogenous deformation above glass transition temperature (Tg). The higher strength and thermal stability of the TFMG is associated with a much higher oxygen concentration in the thin film compared to the BMG. The enhanced mechanical performance of the TFMG compared to the BMG highlights the potential of oxygen in the thermal stability characteristics and deformation capacity of Zr-based thin film metallic glasses.