Hump peak formation and the crystallization in amorphous Al87Co10Ce3 alloy

A distinct hump peak was observed at the scattering angle 2θ ≈ 44° in the X-ray diffraction (XRD) pattern of rapidly quenched amorphous Al87Co10Ce3 alloy. From the XRD patterns of amorphous Al–Co–Ce alloys with different compositions, it is found that the intensity of the hump peak increases as the Co/Ce atomic ratio increases, while the prepeak which characterizes the medium-range order (MRO) becomes weak. The hump peak has a close relationship with the glass forming ability in the Al–Co–Ce system. Furthermore, the crystallization behavior of Al87Co10Ce3 alloy was investigated by the DSC and XRD methods. Compared with Al87Ni10Ce3 alloy, Al87Co10Ce3 alloy did not show a single process of grain growth for fcc-Al particle. The formation of a hump peak is presumed to be associated with the presence of pre-existing nuclei of fcc-Al and Co2Al9 in as-quenched amorphous Al87Co10Ce3 alloy.