The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 03, 2002
Filed:
Jun. 19, 2000
Hiroshi Hasegawa, Saitama, JP;
Yoichi Hirose, Saitama, JP;
Showa Denko K.K., Tokyo, JP;
Abstract
Processes for the preparation of a sintered alloy comprising R Fe B as a magnetic phase constituting a main phase include a binary alloy process wherein a main phase alloy having a lower R content than the above phase is mixed with a grain boundary phase alloy rich in R component and serving as a liquid phase in the sintering in order to prepare a mixture to be used as the starting material. The conventional main phase alloy has a structure comprising the R Fe B phase and, in addition, a large amount of an easily oxidizable lamella R-rich phase and a harmful dendrite &agr; phase. On the other hand, the main phase alloy of the invention has a low dendrite a phase content and a low lamella R-rich phase and contains a lamella &agr; Fe phase. This contributes to excellent oxidation resistance and improved properties of the magnet. The preparation of a sintered magnet by mixing the main phase alloy with the grain boundary phase alloy by the binary alloy method can reduce abnormal growth of crystal grains.