A metallographic study of sintered SmCo5compacts

Metallographic and microprobe analyses have been carried out on bulk SmCo
5
alloy and several series of SmCo
5
compacts. The phases present in SmCo
5
magnets and the disposition of these phases as a function of composition and heat treatment are reported. The results show that rapid and extensive interaction occurs between the sintering aid and the SmCo
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grains during the sintering process. Studies of the homogenization process in SmCo
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indicate that the hypostoichiometric alloy, i.e., less than 33.8 wt% Sm, is formed by Co pairs occupying Sm sites as originally hypothesized by Buschow and Van der Goot.