Ball-milled hydrides, microstructural

Figure 2.50 shows the microstructure of the powder after milling for 15 min with the addition of 5 wt.% Inco m-Ni and n-Ni. The distribution of m-Ni is not quite uniform (Fig. 2.50a) in contrast to that of n-Ni which shows a very uniform distribution of Ni particulate (bright specks) in the entire mass of the powder (Fig. 2.50b). The average ECD particle size of the powder milled with the m-Ni additive is slightly larger than that of the one milled with n-Ni, although both are below the 1 pm mark. The XRD pattern in Fig. 2.51a shows that the microstructure of both powders consists of hydride phases 3- and y-MgH2, Ni, and a small amount of retained Mg and MgO that is formed during XRD test from the retained Mg. Table 2.19 shows grain size of the phases in the ABCR MgH2 ball-milled with Inco m-...

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