The development of high energy product permanent magnets from 2:17 RE-TM alloys

The remanence, Br, of sintered 2:17 RE-TM permanent magnets depends on saturation magnetization, Ms, particle alignment, and packing density. Methods to estimate upper bounds for Msand energy product, (BH)max, as a function of composition are presented. As Bris limited by processing variables, (BH)maxis limited by intrinsic coercivity,MHc, and loop squareness. The coercivities of the 2:17 RE-TM permanent magnets are controlled by the alloy microstructures and the compositions of the phases comprising these microstructures. Some aspects of the response of these alloy systems to compositional and heat treating variables are discussed in light of a model proposed for their metallurgical behavior.