The effects of Si substitution on structure and magnetic properties in mischmetal-Fe-B ribbons

In 1980s´, Nd₂Fe₁₄B magnet was invented, since then almost all kinds of rare-earth elements especially light rare earth and mischmetals have been used to fabricate permanent magnets with 2:14:1 structure. However, most of the investigations about mischmetal-based permanent magnets concentrated on their intrinsic properties [1], and the coercivity and energy product are seldom referred. The main reason is that the traditional processes obtain few satisfactory results without Nd. Recently, with the widening of the price gap between Nd and Ce, more efforts were made on Ce-based [2] and mischmetal-based magnets. However, the properties of Nd free R₂Fe₁₄B magnets still have rise space. Correlation studies [3] shown that the substitution of Si for Fe can enhance the permanent magnetic properties for the magnets with 2:14:1 structure. In this work mischmetal-based magnetic ribbons with nominal composition of (La_0.35Ce_0.65)₂Fe_14-xSi_xB (x=0.5, 1.0, 1.5, 2.0) were prepared by melt-spinning method, commercial mischmetal were used as the raw materials. The effect of Si substitution for Fe on phase formation and magnetic properties were studied.