Zr-Co-Al bulk metallic glass composites containing B2 ZrCo via rapid quenching and annealing

As a promising remedy for overcoming the limited ductility and work softening of bulk metallic glasses (BMGs), BMG composites incorporating a B2 crystalline phase have attracted considerable attention. Here, we explore the formation of Zr-Co-Al BMG composites by quenching alloys Zr55Co31Al14, Zr54.5Co33.5Al12, Zr53.5Co36.5Al10, Zr52.5Co37.5Al10, and Zr43Co43Al14. We found the first alloy fully amorphous whereas the fifth was fully crystallized upon quenching. The other three were quenched to generate composite structures, with a higher fraction of B2 ZrCo phase with increasing Co/Zr ratio and decreasing Al content. For comparison, the formation of B2 ZrCo in annealed Zr55Co31Al14 was also studied. For both approaches the influence of crystalline phases on hardness was examined.