The influence of cooling rate on the hardness of Pd-Si binary glassy alloys

The influence of cooling rate on the hardness of the as-prepared Pd81Si19 binary glassy alloys has been studied. It has been found that decreasing the employed cooling rate would increase the hardness and decrease the full width at half maximum (FWHM) of their X-ray diffractometry (XRD) spectrum. The microhardness of the bulk glassy alloy prepared by air cooling is about 453.9 kg/mm(2), 41% higher than that of the rapid solidified glassy ribbons. Through careful investigation of the FWHM of the XRD spectrum and the high resolution transmission electron microscope images, the cooling rate dependence of hardness is suggested to be attributed to the difference in structural uniformity and the resulted local ordering atomic clusters (medium-range order (MRO) regions) within the as-prepared glassy samples. Moreover, it has been found that decreasing cooling rate would promote the formation of denser atomic configuration and the local ordering clusters (MRO).