Preparation of non-magnetic and ductile Co-based bulk metallic glasses with high GFA and hardness

Co(Fe,Ni)-based bulk metallic glasses (BMGs) characterized with super-high hardness and strength are generally brittle and strong magnetic, significantly undercutting their momentous applications as coating materials. Here we report Co92-xNi2Ta6Bx (x = 29–35) non-magnetic BMGs with a combination of appropriate plasticity and GFA, as well as superhigh hardness and strength. BMG Rods with maximum diameters up to 2.5 mm were fabricated by copper mold casting method. All alloys exhibit superhigh compressive fracture strength of 5.21–5.63 GPa, high hardness of 1290–1410 HV and plasticity of 1.2–3.5%. Besides, the amorphization can effectively decrease the magnetization and all the alloys show non-magnetic properties at glassy state. The partial crystallization in the high B content glassy alloys will not significantly change the non-magnetic or poor-magnetic feature. It is also found that the increase of B content can substantially improve the thermal stability of the glassy alloys and inhibit the formation of strong magnetic phases. These Co-based alloys are promising candidates for the future application of spray coating materials.