Thermal stability of nanostructured Sm2Fe17Cx compounds prepared by ball milling

The thermal stability of ball-milled nanocrystalline Sm2Fe17Cx interstitial compounds has been investigated. Sm2Fe17Cx decomposes into a mixture of phases upon annealing above a certain decomposition temperature, T-d1, which:depends on the carbon concentration in the compound. Annealing above a certain temperature T-d2(>T-d1); the-Sm2Fe14C phase starts to form. The amount of the Sm2Fe14C phase increases with increasing annealing temperature at the expense of the Sm2Fe17 carbide until T-r1 at which temperature Sm2Fe14C starts to recombine with other phases to form the Sm2Fe17 carbide. For the starting composition with x<1.5, the Sm2Fe17Cx single phase can be recovered above the recovery temperature T-r2(>T-r1). (C) 1996 American Institute of Physics.