R-T-B-BASED SINTERED MAGNET

• Main Authors: MIWA MASASHI, KUDO HIKARI
• Format: Patent
• Language: English; Japanese
• Published: 03.10.2019
• Subjects: ALLOYS; BASIC ELECTRIC ELEMENTS; CHEMISTRY; ELECTRICITY; FERROUS OR NON-FERROUS ALLOYS; INDUCTANCES; MAGNETS; METALLURGY; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; TRANSFORMERS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

To provide an R-T-B-based sintered magnet having high coercivity and residual magnetic flux density at room temperature and a high coercive force even at a high temperature.SOLUTION: The sintered magnet contains a rare earth element R (for example, Nd and Pr), a transition metal element T (for example, Fe and Co), B, Cu, and Ga, and includes a plurality of main phase particles 4 (crystal grains of RTB) and a plurality of grain boundary multiple points surrounded by three or more of the main phase particles 4. The plurality of grain boundary multiple points is classified into transition metal rich phase 6 (for example, RTGa) and R rich phase 8. The R rich phase 8 is classified into a Cu poor phase 8A and a Cu rich phase 8B. The following formulas 1, 2 are satisfied in a cross section of the sintered magnet. N1 is the number of transition metal rich phases 6, N2 is the number of Cu poor phases 8A, and N3 is the number of Cu rich phases 8B. 0.30≤N1/(N1+N2+N3)≤0.60(1), 0.03≤N3/N2≤0.20 (2)SELECTED DRAWING: Figure 2 【課題】室温で高い保磁力及び残留磁束密度を有し、高温でも高い保磁力を有するＲ-Ｔ-Ｂ系焼結磁石を提供する。【解決手段】焼結磁石は、希土類元素Ｒ（例えばＮｄ及びＰｒ）、遷移金属元素Ｔ（例えばＦｅ及びＣｏ）、Ｂ、Ｃｕ及びＧａを含有し、複数の主相粒子４（Ｒ２Ｔ１４Ｂの結晶粒）と、三つ以上の主相粒子４に囲まれた複数の粒界多重点を備える。複数の粒界多重点は、遷移金属リッチ相６（例えばＲ６Ｔ１３Ｇａ）及びＲリッチ相８に分類される。Ｒリッチ相８は、Ｃｕプア相８Ａ及びＣｕリッチ相８Ｂに分類され、焼結磁石の断面において下記式１及び２が満たされる。Ｎ１は、遷移金属リッチ相６の個数であり、Ｎ２はＣｕプア相８Ａの個数であり、Ｎ３はＣｕリッチ相８Ｂの個数である。０．３０≦Ｎ１／（Ｎ１＋Ｎ２＋Ｎ３）≦０．６０（１）、０．０３≦Ｎ３／Ｎ２≦０．２０（２）【選択図】図２