Effect of the variation in Sm/Cu/Zr content on phase stability of an Sm(Co,Fe,Cu,Zr)/sub 7.4/ permanent magnet alloy

The effect of composition variation on the phase stability of an Sm(Co,Fe,Cu,Zr)/sub 7.4/ system was studied to provide information on interpreting phase changes after partitioning of composition in the heat treatment of this alloy. Three quasi-binary phase diagrams were obtained by X-ray diffractometry, differential thermal analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The zonal and grain boundary phases which are precipitates at the later stages of permanent magnet heat treatment can be explained by these phase diagrams. The major phase of all the alloys studied is either the 2:17 H or 2:17 R phase. However, additional phases appear as a result of compositional variations. >