Effect of copper addition on the glass forming ability in Pd-Si binary amorphous alloying system

The effect of copper addition on the glass forming ability in Pd-Si amorphous alloys was systematically studied by X-ray diffraction and differential scanning calorimeter with a binary alloy series of Pd81+xSi19-x (x=0, 1, 1.5, 2, 2.5, 3, 4) and a ternary alloy series of Pd83.5-xCuxSi16.5 (x=0, 2, 4, 6, 8, 10, 12). It has been found that the critical size of the Pd-Si alloys could be improved significantly from 8mm to 15mm and ΔTx could be enhanced from 18.7 K to 54.7 K with the addition of copper. The determined activation energy demonstrates that Cu additions improve the thermal stability of the system significantly. The different results of the measured criteria to evaluate the GFA for the Pd-Si and the Pd-Cu-Si alloys may be linked to a different crystallization behavior. The enhanced GFA is linked to a more thermodynamically stable liquid and a reduction of atomic diffusion in the ternary alloy by Cu addition.