Js. Fang et al., MAGNETIC-PROPERTIES AND STRUCTURE OF ND-(FE,B) NANOCOMPOSITE ALLOYS WITH FIXED FE B RATIOS AT 4-14/, JPN J A P 1, 36(10), 1997, pp. 6316-6324
Magnetic properties and nanostructure of pseudobinary Nd-(Fe,B) alloys
with lived Fe/B ratios of 4, 6, 8, 10, l4, respectively and Nd=3 to I
I at %, prepared by melt-spinning and rapid thermal annealing (RTA), w
ere investigated. Magnetic properties were found to depend on nanostru
cture, particularly the size and size distribution of hard and soft ph
ases, which were in turn determined by Nd contents and Fe/B ratios tog
ether with RTA processing. The maximum energy products, (BH)(max), of
the optimally RTA treated 11 at.%Nd flakes with Fe/B=IO and I4 are 19
MGOe and l8.8MGOe, respectively. However, the remanence decreases with
increasing Nd contents due to the decreasing amount of Fe nanocrystal
. The Fe/B=6 alloys with Nd < 6 at.% showed very low intrinsic coerciv
ity (iHc) and (BH)(max), which were attributed mainly to impurity phas
es, typically Nd2Fe23B3 and Nd1.1Fe4B4. The reversible and irreversibl
e magnetization behaviors were also studied in order to qualify the ex
change coupling interaction between hard and soft phases of alloys, Th
e variation in nucleation field at the same Fe/B ratio of 14 was found
to depend on volume fraction of hard phase formation as well as the s
ize distribution of the two phases.