Diffusion behavior of iron and samarium atoms in Sm2Fe17 alloy compound layer

Abstract

The Sm2Fe17 alloy compound has been widely studied and used as a precursor for Sm2Fe17Nx rare-earth permanent magnets. However, the growth mechanism of Sm2Fe17 remains unclear. In this study, based on the high temperature diffusion method, a Sm2Fe17 layer was prepared by fabricating a Sm–Fe (sat)/Fe(s) diffusion couple in the temperature range of 1060–1140 °C. Results indicated that the diffusion of Fe and Sm atoms is the rate-determining step in the growth of the Sm2Fe17 layer. The atomic concentrations of Fe and Sm in samples with different holding times at 1060–1140 °C were analyzed using an electron microprobe, which revealed that the growth of the Sm2Fe17 layer primarily depended on the diffusion of Fe atoms. The diffusion coefficients of Fe atoms in the Sm2Fe17 layer were 2.33 × 10−9, 4.29 × 10−9, and 5.37 × 10−9 cm2 s−1 at 1060, 1100, and 1140 °C, respectively. Moreover, the relationship between the diffusion coefficient of Fe atoms (DFe) and temperature (T) was obtained.