Effect of Cu Presence on Evolution of Mechanical and Magnetic Properties in a Novel Fe-Based Bulk Metallic Glass During Partial Annealing Process

Abstract

Fe-based bulk metallic glasses (BMGs) often demonstrate extremely poor toughness at room temperature, which seriously limit their widespread application. This study is focused on the improvement of mechanical properties (especially toughness) and ferromagnetic manner of a new Fe-based BMG by using partial annealing and minor addition of Cu as an alloying element simultaneously. The results revealed that the volume fraction of crystalline phases increased with the minor addition of Cu during the partial annealing process. Therefore, maximum hardness and toughness were observed in the alloy with 0.25 at. pct Cu after annealing within a temperature range of the fourth crystallization stage due to the high Poisson’s ratios (υ) of this element and the presence of nano-crystalline phases in the amorphous matrix with an optimal average size. Also, saturation magnetization of the as-cast BMG increased with the minor addition of Cu due to the formation of short-range order regions. While with addition of Cu, this magnetic parameter was reduced in annealed alloys due to an increase in the concentration of non-magnetic Cu atoms around the α-Fe nano-crystals.