R-T-B based sintered magnet and production method for same, and rotary machine

摘要

An R-T-B sintered magnet including a composition containing a rare earth element, a transition element and boron, containing essentially no dysprosium as a rare earth element, and having crystal grains with a composition containing a rare earth element, a transition element and boron, and grain boundary regions formed between the crystal grains, wherein the triple point regions which are grain boundary regions surrounded by 3 or more crystal grains have a composition containing a rare earth element, a transition element and boron and have a higher mass ratio of the rare earth element than the crystal grains, the average value of the area of the triple point regions in a cross-section being no greater than 2 μm2 and the standard deviation of the area distribution being no greater than 3.

主权项

1. An R-T-B sintered magnet comprising a composition containing a rare earth element, a transition element and boron,
the R-T-B sintered magnet including essentially no dysprosium as a rare earth element, the R-T-B sintered magnet having crystal grains with a composition containing a rare earth element, a transition element and boron, and grain boundary regions formed between the crystal grains, wherein the crystal grains include an R2T14B phase, and wherein triple point regions which are the grain boundary regions surrounded by 3 or more of the crystal grains include a phase with a higher R content ratio than the R2T14B phase based on mass, and the triple point regions having a higher mass ratio of the rare earth element than the crystal grains, the average value of the area of the triple point regions in a cross-section being no greater than 2 μm2 and the standard deviation for the area distribution being no greater than 3, and the content of rare earth elements in the triple point region being 80 to 99 mass %, and the standard deviation of the content distribution being no greater than 5, wherein R represents a rare earth element other than dysprosium, T represents a transition element and B represents boron.