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0.7<br />
0.6<br />
0.5<br />
Wt. % H absorbed<br />
0.4<br />
0.3<br />
0.2<br />
0.1<br />
0.0<br />
0 500 1000 1500 2000 2500 3000 3500<br />
time (s)<br />
Figure 19: Composition curve for hydriding of LaNi 5 prepared in Fritsch Pulverisette<br />
Mill at 300 rpm.<br />
In an attempt to enhance activation by milling, the vial containing the sample was<br />
filled with 3.7 atm H 2 prior to milling. Milling in a reactive atmosphere is referred to as<br />
reactive milling. This was accomplished by using a vial cap equipped with inlet and<br />
outlet valves to change the milling atmosphere. This type of vial was only available for<br />
the Fritsch Pulverisette mill. By reactive milling, it was projected to increase the<br />
brittleness of the alloy by the dissolution of hydrogen in the metal, inducing lattice<br />
expansion in the crystal structure and causing internal stress. The sample took up 0.56%<br />
H after thermal activation, which was less than, but close to, the value determined for the<br />
sample prepared in an argon atmosphere. It was reported previously that reactive milling<br />
under approximately 10 atm of H 2 , using similar milling parameters (Fritsch mill, 30:1<br />
50
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