A New Ni-Based Metallic Glass with High Thermal Stability and Hardness

Glass forming ability (GFA), thermal stability and microhardness of Ni 51？xCu xW 31.6B 17.4 ( x = 0, 5) metallic glasses have been investigated. For each alloy, thin sheets of samples having thickness of 20 μm and 100 μm were synthesized by piston and anvil method in a vacuum arc furnace. Also, 400 μm thick samples of the alloys were synthesized by suction casting method. The samples were investigated by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). Crystallization temperature of the base alloy, Ni 51W 31.6B 17.4, is found to be 996 K and 5 at.% copper substitution for nickel increases the crystallization temperature to 1063 K, which is the highest value reported for Ni-based metallic glasses up to the present. In addition, critical casting thickness of alloy Ni 51W 31.6B 17.4 is 100 μm and copper substitution does not have any effect on critical casting thickness of the alloys. Also, microhardness of the alloys are found to be around 1200 Hv, which is one of the highest microhardness values reported for a Ni-based metallic glass until now.