The Effect of Purification on the Glass-Forming Ability of a Pd-Cu-Si Alloy

The copper mold casting method is now commonly used for preparing bulk metallic glasses (BMGs). In the present work, it was found that, by employing the copper mold casting method, Pd_77.5Cu₆Si_16.5 (at. pct) glassy rods with 1-mm diameter could be prepared, while the ϕ2-mm Pd_77.5Cu₆Si_16.5 casting rod possesses some crystalline phases embedded within the glass matrix, confirming that the critical size of the glassy alloy is about 1 mm. By melt purification with fluxing treatment, the critical size of the glassy rod prepared by copper mold casting is increased to 4 mm. Based on thermal property analysis, it was found that melt purification by the fluxing method can greatly enhance the thermal stability and increase the glass forming ability (GFA) of the Pd-Cu-Si alloys. The as-prepared ϕ4-mm Pd-Cu-Si glassy rod exhibits a reduced glass transition temperature (T _rg ) of 0.599, a supercooled liquid region (ΔT) of 74 K (74 °C), and a γ parameter of 0.419.