Structural, solid–gas and electrochemical characterization of [formula omitted]-rich and [formula omitted] amorphous-rich nanomaterials obtained by mechanical alloying

Abstract

Using a planetary ball mill and starting from a mixture of Mg and Ni with an atomic ration of 2:1, we successfully elaborated a nanocomposite material formed by the Mg 2 Ni phase in high proportion, some residual Ni and an amorphous phase. The synthesis of this composite proceeded at milling intensities 7 and 10, corresponding to 3.5 and 10 W/g shock power, respectively, after 18 and 4 h. The best hydrogen absorption capacity reported, 3.75 H mol - 1 (3.53 wt%) is for the composite synthesized for 24 h at 3.5 W/g shock power. Using the same planetary ball mill and starting from a mixture of Mg 2 Ni and Ni with a Mg atomic content ranging from 40 to 60 at%, we elaborated amorphous phase alloys with little quantities of residual Ni. The synthesis of the amorphous phase proceeded at 6.49 W/g shock power, for milling durations ranging from 8 to 10 h for Mg 40 Ni 60 and Mg 60 Ni 40 samples, respectively. The best electrochemical capacity (470 mAh/g) was obtained for the Mg 50 Ni 50 sample obtained at milling duration 10 times shorter than that reported in the literature.