Variation of the Magnetic Properties of Sm (Co, Cu)5 Alloys with Temperature

Publisher Website
Google Scholar
Abstract
Modified permanent magnets of rare earth cobalt compounds, R(Co, Cu)5, are known as alloys having a complex decomposition mechanism. Studies of the variation of magnetic properties with temperature were carried out for Sm(Co, Cu)5 alloys containing 0 to 75 at% copper. The optimum area for magnetic values was shifted toward the samarium-poor side from the line connecting the compound SmCo5 with SmCu5. Differential thermal analysis (DTA) revealed that the endothermic reaction temperatures were around 920°C and scarcely varied in alloys containing from 16 to 66 at% copper. This suggests that the phase transformation may occur at this temperature regardless of different copper contents. In Sm(Co, Cu)5 alloys a single Curie point (Tc) was observed on rapid heating from the as-cast condition, and two points on slow cooling after heating at 1000°C for 30 min. One of the Curie points belongs to a SmCo5 structure type and the other to a compound isostructural with Sm2Co17. From the results of DTA and measurements of Tc and magnetic values, a hypothetical Sm–Co–Cu ternary phase diagram is proposed, in which the alloys initially containing 24 to 40 at% copper may decompose spinodally.

This publication has 8 references indexed in Scilit: