Nanocrystalline Nd(6)Fe(88-x)M(x)B(6) (M=Ti or V) magnets by rapid thermal annealing

Nanocrystalline structures were obtained by a rapid thermal annealing (RTA) process with a heating rate of 600 degrees C/min for a soaking time of 2 minutes for melt-spun Nd6Fe(88)-xMxB(6) amorphous alloys (M= Ti or V, x= 0 similar to 5). Exchange coupling interaction between the magnetically hard and soft phases was studied with the delta M plots. Addition of Ti or V to replace iron is effective in increasing remanence ratio, Mr/M(2T), and energy product of the modified alloys, especially that modified by V, although both saturation magnetization and remanence are decreased due to magnetic dilution. High resolution TEM studies showed that both Ti and V is effective in refining grain size of both hard and soft phases to 20 similar to 23 nm compared with 50 similar to 52 nm for the x= 0 alloy. The substitution with V results in a decrease in coercivity despite of refined grains.