THERMAL-STABILITY OF NANOSTRUCTURED SM2FE17CX COMPOUNDS PREPARED BY BALL-MILLING

The thermal stability of ball-milled nanocrystalline Sm2Fe17Cx interst itial compounds has been investigated. Sm2Fe17Cx decomposes into a mix ture of phases upon annealing above a certain decomposition temperatur e, T-d1, which:depends on the carbon concentration in the compound. An nealing above a certain temperature T-d2(>T-d1); the-Sm2Fe14C phase st arts to form. The amount of the Sm2Fe14C phase increases with increasi ng annealing temperature at the expense of the Sm2Fe17 carbide until T -r1 at which temperature Sm2Fe14C starts to recombine with other phase s to form the Sm2Fe17 carbide. For the starting composition with x<1.5 , the Sm2Fe17Cx single phase can be recovered above the recovery tempe rature T-r2(>T-r1). (C) 1996 American Institute of Physics.