ISSN 2594-5327
49º Congresso anual — Vol. 49, Num. 1 (1994)
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This work presents and discusses some aspects of Nd-Fe-B magnets processing technology, namely, sintering and hot deformation. The former technique was studied mainly with respect to densification mechanism, grain growth, and evolution of magnetic alignment. From these studies a model was devised according to which particles are kept in place by rapid neck formation, leading to the so-called skeleton structure. Aligned particles form large aggregates, while non-aligned ones are isolated by the intergranular phase. This configuration conducts to an Ostwald Ripening type of growth in which the aggregates grow at the expense of the non-aligned particles, thus increasing the magnetic orientation degree. For the hot deformation studies, Nd₁₈.₉Fe₆₉.₇Cu₁.₂Nb₁Al₁ ingots were obtained. Microstructure included fine grains near the mould wall which are followed by a columnar region, and by large grains in the ingot centre. Deformation was performed by hot pressing and by hot rolling and general fracturing of the columnar dendrites was observed. Identification of the intergranular and intragranular phases was carried out and microstructural parameters such as grain size, intergranular fraction, contiguity and alignment degree were determined. Corrosion studies showed that hot deformed samples exhibit a better corrosion resistance.
Palavras-chave
Nd-Fe-B magnets, Sintering, Hot deformation, Magnetic alignment, Microstructure, Corrosion resistance
Como citar
Ferrante, Maurizio; Sinka, Viliam; Assis, Odilio B.G.; Oliveira, Ivanir L. de; Zampieron, João V..
Nd-Fe-B Magnets Produced by Sintering and by Hot Deformation: Technology, and Magnetic Properties,
p. 588-601.
In: 49º Congresso anual,
Rio de Janeiro, Brasil,
1994.
ISSN: 2594-5327, DOI 10.5151/2594-5327-49v2-57-70
