SEM STUDY ON THE EFFECT OF Zr ADDITION ON THE MICROSTRUCTURES AND PROPERTIES OF A Sm(Co, Fe, Cu, Zr)7. 46 MAGNET ALLOY.

Scanning electron microscopy (SEM) was used to study the effect of Zr addition on the magnetic properties of a Sm(Co//0//. //6//7// minus //xFe//0//. //2//8Cu//0//. //0//5Zr//X)//7//4//6 magnet, where x equals 0. 01, 0. 02 and 0. 03. Five phases are observed from the microstructures, they are cell interior, cell boundary, platelet structure, grain boundary phase and large segregate, the last being a Zr rich phase. An increase in iHc as the Zr additiion increased is most likely arisen from the refinement of cellular structure, and the increase of the domain wall pinning effect. Besides, the grain boundary phase is also believed to have a strong contribution to iHc because it is dense and weaved around the grain surface. The Zr rich large segregates are not likely to have a distinct contribution to the domain wall pinning because they are large in size but few in number, at least for the compositions studied.