Magnetic properties and microstructure of lanthanum-doped Mn-Al and Mn-Al-C permanent magnets

✍ Scribed by J. H. Huang; P. C. Kuo; C. H. Chen

• Publisher: Springer
• Year: 1994
• Tongue: English
• Weight: 788 KB
• Volume: 29
• Category: Article
• ISSN: 0022-2461
• DOI: 10.1007/bf00356528

✦ Synopsis

) lOo-xLax alloys, with x up to 0.9, were synthesized and examined by powder X-ray diffraction and magnetic measurements. Lattice parameters, Curie temperature, T c, coercivity, iHo, and saturation magnetization, M s, were determined. Phase analysis revealed that AlaLaMn 4 precipitates were produced due to the lanthanum addition. A slight increase in the iH c was observed for x_< 0.3 in the cast MnAILa alloys. No significant changes in lattice parameters and T c were observed for these lanthanum-doped alloys. For sintered isotropic magnets, which were prepared by conventional powder metallurgy processes, the iH o was enhanced on doping with lanthanum. The (BH)max values were also increased. The increment of (BH)ma, was about 16% for x= 0.3. Higher lanthanum intensity at grain boundaries was observed on examination of the energy-dispersive X-ray spectra (EDX). The reasons for the increase in iHc may be due to the fine precipitates of lanthanum in the grain boundaries.