A contribution to the Sm–Co phase diagram

Abstract

The Co-rich part of the Sm-Co system has been investigated by X-ray diffraction, metallographic and thermoanalytic methods. The existence of five closely related compounds (Sm2Co7, SmCos_x, SmCos, SmCos+x and Sm2Co~7) has been confirmed. A tentative phase diagram of the Co-rich part of the Sm-Co system is presented. The practical difficulties encountered in the construction of this phase diagram are discussed.

Atomistic simulation for disordered rare-earth compounds SmCo7 and Sm(Co,Ti)7

“…2(e1) and (e2)), it can be found that, the distance between (2 0 0) and (0 0 2) peaks in SmCo 5 is significantly larger. Both experiment [23] and our calculation (Table 2) show that, comparing with SmCo 5 structure, the lattice constant a in SmCo 7 is reduced and c is increased, which resulting a shifting of the (2 0 0) peak to high angle and the (0 0 2) peak to low angle.…”

Experimental and modeling studies on phase stability of nanocrystalline magnetic Sm2Co7

“…the hexagonal ␣-Sm 2 Co 7 as a dominant phase and the rhombohedral ␤-Sm 2 Co 7 with the Gd 2 Co 7 -type crystal structure as a secondary phase. It should be noted that in the conventional polycrystalline alloys, the ␤-Sm 2 Co 7 phase can exist stably only at temperatures higher than 1435 K [28]. Thus the nanocrystalline Sm 2 Co 7 has different phase stability as compared with the conventional coarse-grained polycrystalline alloy.…”

“…In the RECo 5 alloy systems, the strong magnetic anisotropy mainly results from the Co atoms at the '2c' site in the crystal structure. For the Sm 2 Co 7 alloy, the axis ratio is c/a = 4.82 for the ␣-Sm 2 Co 7 phase and c/a = 7.22 for the ␤-Sm 2 Co 7 phases, respectively [28]. This implies that the ␤-Sm 2 Co 7 phase may have different magnetocrystalline anisotropy from that of the ␣ phase.…”

“…As the phase constitution is different in the coarse-grained and nanocrystalline Sm 2 Co 7 alloys, it is important to investigate the phase stability in the nanocrystalline alloy. Previous studies have shown that the crystal structure of Sm 2 Co 7 phase can be developed from the SmCo 5 structure by replacing certain Co atoms with Sm atoms [28,38]. In the RECo 5 alloy systems, the strong magnetic anisotropy mainly results from the Co atoms at the '2c' site in the crystal structure.…”

A revision of the Sm-rich region of the Sm–Co system

“…The Sm-Co system has attracted much attention [5][6][7][8][9][10][11][12][13][14][15] for the excellent magnetic properties of the Co-rich alloys. The most recent experimental study of the Sm-Co system was carried out by Ge et al [5].…”