Production of (Nd,MM) 2(Fe,Co,Ni) 14B-type sintered magnets using a binary powder blending technique

• Published in: Journal of alloys and compounds Vol. 298; no. 1; pp. 319 - 323
• Main Authors: Madaah Hosseini, H.R, Kianvash, A, Seyyed Reihani, M, Yoozbashi Zadeh, H
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 28-02-2000; Elsevier
• Subjects: Applied sciences; Binary alloy sintering method; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic properties and materials; Metal powders; Metals. Metallurgy; Nd–Fe–B alloys; Permanent magnet materials; Permanent magnets; Physics; Powder metallurgy. Composite materials; Production techniques; Studies of specific magnetic materials; Permanent magnet materials; Binary alloy sintering method; Nd–Fe–B alloys; Phase composition; Experimental study; Powder metallurgy; Fabrication property relation; X ray diffraction; Optimization; Grain boundary; Dual phase structure; Sintering; Phase boundaries; Chemical composition; SEM; Permanent magnet; Microstructure; Iron base alloys; Magnetic properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/S0925-8388(99)00667-2

The anisotropic (Nd,MM)
2(Fe,Co,Ni)
14B-type magnets were produced using the binary alloy sintering method (MM denotes a Misch-metal). The composition of the master alloy was close to stoichiometric Nd
2Fe
14B compound, while that of the sintering aid was MM
38.2Co
46.4Ni
15.4. The microstructures of sintered magnets were investigated using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray detector (EDX). X-ray diffractometry (XRD) was also employed for phase analysis. The optimum magnetic properties were obtained for a composition of Nd
11.9MM
2.9Fe
73.9Co
3.3Ni
1.1B
6.9 made of 90 wt.% master alloy and 10 wt.% sintering aid. The two main phases, i.e. the (RE)
2(TM)
14B phase as the matrix and the rare-earth rich phase as the grain boundary phase, were identified in the specimens. No Nd
1.1Fe
4B
4 boride phase was observed in these samples, while there was some Fe-rich phase in the specimens with lower amount of sintering aid. The permanent magnet properties of the specimen in the optimum condition were as follows:
B
r=11.2 kG,
H
cj=11.5 kOe and (
BH)
max=32 MGOe with a Curie temperature of 351°C.