Patent ID: 6386269
Filing Date: 2002-05-14
Classification: B82Y,C22C,H01F

Abstract:
A method of manufacturing thin plate magnets having a fine crystalline structure comprising the steps of (a) providing an alloy melt having a compositional formula of Fe100âˆ’xâˆ’yâˆ’zRxAyMz or (Fe1âˆ’mCom)100âˆ’xâˆ’yâˆ’zRxAyMz, where R is at least one element selected from the group consisting of Pr, Nd, Tb and Dy, A is at least element selected from the group consisting of C and B, and M is at least one element selected from the group consisting of Al, Si, Ti, V, Cr, Mn, Ni, Cu, Ga, Zr, Nb, Ag, Hf, Ta, W, Pt, Au and Pb, and wherein 1&lE;x&lE;6 at %, 15&lE;y&lE;30 at %, 0.01&lE;z&lE;7 at %, and 0.001&lE;m&lE;0.5, (b) providing a rotatable cooling roller in a reduced pressure inert gas atmosphere at no more than 30 kPa, (c) rotating said cooling roller at a circumferential speed of 1 to 10 m/s, (d) flowing said alloy melt onto said rotating roller of (c) so as to directly cast thin plate permanent magnets having a thickness of 70 to 500 &mgr;m and containing fine crystals having a mean crystalline grain diameter of no more than 50 nm, at least 90% of said fine crystals being comprised of a crystalline structure wherein an Fe3B compound and &agr;-Fe coexist with a compound phase having an Nd2Fe14B crystalline structure, and exhibiting magnet properties of iHc&gE;2.5 kOe and Br&gE;9 kG.