THE THERMAL-STABILITY OF AMORPHOUS HYDRIDE MG50NI50H54 AND MG30NI70H45

The thermal stability of amorphous ternary hydrides Mg50Ni50H54 and Mg 30Ni70H45 and their corresponding amorphous binary alloys Mg50Ni50 and Mg30Ni70 were studied with X-ray diffraction (XRD) and differential s canning calorimetry (DSC). Samples of the amorphous alloys were prepar ed by mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gaseous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most of their hydrogen bef ore the crystallization of the essentially hydrogen depleted amorphous alloy began. The crystallization temperature of amorphous Mg50Ni50H54 was elevated and that of amorphous Mg30Ni70H45, did not change relati ve to that of the original binary amorphous alloys. This is very excep tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on the crystallization of amorphous alloys was d iscussed.