Effect of Fe and Annealing Treatment on Hydrogenation Behavior of Sm(CobalFexCu 0.068Zr0.034)7.33 ( \(\mathbf {{\textit {x}} = 0.237,0.251,0.265}\) ) Alloys

The effect of Fe on hydrogenation behavior of 2:17 type SmCo alloys was investigated. The as-cast Sm(Co
_bal
Fe
_x
Cu
_0.068
Zr
_0.034
)
_7.33
alloys with (x= 0.251) and (x=0.265) are decrepitated under hydrogen pressure of 0.3 MPa at room temperature, whereas the as-cast alloy with (x=0.237) is not decrepitated. The hydrogenation ability for as-cast alloys is obviously improved with the increase of Fe content. With the increase of Fe content, the network structures that consist of easily hydrogen-decrepitation (HD) phase, including 1:5 phase and 2:7 phase, become fine and well-distributed. The network structures for heat-treated alloys are eliminated after heat treatment at 1190 °C. All heat-treated alloys can be decrepitated under hydrogen pressure of 0.3 MPa at room temperature. The hydrogenation ability of heat-treated alloys are improved with increasing of Fe content. HD for as-cast alloys and heat-treated alloys result from improvement of hydrogenation abilities for 1:7 phase due to expanded unit cells after part of Fe atoms entering into 1:7 matrix phase.