Shin-etsu Chemical Co., Ltd.

Takahiro Hashimoto

Takehisa Minowa

Koji Sato

Koichi Hirota

Hajime Nakamura

Kenji Yamamoto

Kazuaki Sakaki

Osamu Kohno

Yoshihiro Umebayashi

Masayuki Kamata

Fukuji Matsumoto

Kazuya Fukui

Ryuji Nakamura

Eiji Uesaka

Kenji Imamura

When a powder material () is molded by introducing the material into a cavity () between a lower punch () and a die (), compression molding the material between upper and lower punches (and) into a compact () of desired shape, and moving up the lower punch () to eject the compact (), a lubricant is applied to the interior surface of the die () by fitting a pad () around the lower punch () and impregnating the pad with the lubricant. Since the lubricant is applied on every molding operation, molding operation can be continuously carried out.

Powder molding apparatus and manufacture of rare earth sintered magnet using the apparatus

An R&#x2014;(Fe,Co)&#x2014;B base sintered magnet consisting essentially of 12-17 at % of R containing Nd and Pr, 0.1-3 at % of M(typically Si), 0.05-0.5 at % of M(typically Ti), B, and the balance of Fe, and containing R(Fe,Co)B as a main phase has a coercivity of at least 10 kOe. The magnet contains a Mboride phase at a grain boundary triple junction, and has a core/shell structure that the main phase is covered with a grain boundary phase. The grain boundary phase is composed of an amorphous and/or nanocrystalline R'&#x2014;(Fe,Co)&#x2014;M&#x2032; phase consisting essentially of 25-35 at % of R&#x2032; containing Pr, 2-8 at % of M&#x2032; (typically Si), up to 8 at % of Co, and the balance of Fe. A coverage of the main phase with the R&#x2032;&#x2014;(Fe,Co)&#x2014;M&#x2032; phase is at least 50%, and the bi-granular grain boundary phase has a width of at least 50 nm.

R-(Fe, Co)-B sintered magnet and making method

A rare earth sintered magnet is prepared from a corresponding alloy powder, using a mold comprising a die, an upper punch, and a lower punch which is divided into a plurality of punch segments which are independently movable within the die. The method comprises the steps of filling the mold cavity with the alloy powder when one or more selected punch segments are moved to a higher position than the remaining punch segments; moving the selected punch segments down to the position where the selected and remaining punch segments assume the normal shape of the lower punch during the compression step; compressing the alloy powder between the upper and lower punches under a magnetic field while the normal shape of the lower punch is maintained, for thereby molding a compact; and heat treating the compact.

Method for preparing rare earth sintered magnet

A rare earth sintered magnet consists essentially of 26-36 wt % R, 0.5-1.5 wt % B, 0.1-2.0 wt % Ni, 0.1-3.0 wt % Si, 0.05-1.0 wt % Cu, 0.05-4.0 wt % M, and the balance of T and incidental impurities wherein R is a rare earth element, T is Fe or Fe and Co, M is selected from Ga, Zr, Nb, Hf, Ta, W, Mo, Al, V, Cr, Ti, Ag, Mn, Ge, Sn, Bi, Pb, and Zn. Simultaneous addition of Ni, Si, and Cu ensures magnetic properties and corrosion resistance.

R-T-B rare earth sintered magnet

A rare-earth alloy ingot is produced by melting an alloy composed of 20-30 wt % of a rare-earth constituent which is Sm alone or at least 50 wt % Sm in combination with at least one other rare-earth element, 10-45 wt % of Fe, 1-10 wt % of Cu and 0.5-5 wt % of Zr, with the balance being Co, and quenching the molten alloy in a strip casting process. The strip-cast alloy ingot has a content of 1-200 &#x3bc;m size equiaxed crystal grains of at least 20 vol % and a thickness of 0.05-3 mm. Rare-earth sintered magnets made from such alloys exhibit excellent magnetic properties and can be manufactured under a broad optimal temperature range during sintering and solution treatment.

Rare-earth alloy, rare-earth sintered magnet, and methods of manufacturing

A rare-earth alloy ingot is produced by melting an alloy composed of 20&#x2013;30 wt % of a rare-earth constituent which is Sm alone or at least 50 wt % Sm in combination with at least one other rare-earth element, 10&#x2013;45 wt % of Fe, 1&#x2013;10 wt % of Cu and 0.5&#x2013;5 wt % of Zr, with the balance being Co, and quenching the molten alloy in a strip casting process. The strip-cast alloy ingot has a content of 1&#x2013;200 &#x3bc;m size equiaxed crystal grains of at least 20 vol % and a thickness of 0.05&#x2013;3 mm. Rare-earth sintered magnets made from such alloys exhibit excellent magnetic properties and can be manufactured under a broad optimal temperature range during sintering and solution treatment.

A crucible comprising AlOand at least one selected from rare earth oxides inclusive of YOas main components and characterized by firing at 500&#x2013;1,800&#xb0; C., the distribution of the rare earth oxide at a higher proportion in a fine particle portion having a particle size of up to 0.5 mm than in a coarse particle portion having a particle size in excess of 0.5 mm, and the substantial absence of the reaction product of the rare earth oxide with AlOis suitable for the melting of a rare earth alloy.

Crucible for melting rare earth element alloy and rare earth element alloy

An alloy powder for bonded rare earth magnets is prepared by melting an alloy consisting essentially of 20-30 wt % of Sm or a mixture of rare earth elements (inclusive of Y) containing at least 50 wt % of Sm, 10-45 wt % of Fe, 1-10 wt % of Cu, 0.5-5 wt % of Zr, and the balance of Co, quenching the melt by a strip casting technique, to form a rare earth alloy strip containing at least 20% by volume of equiaxed crystals with a grain size of 1-200 &mgr;m and having a gage of 0.05-3 mm, and heat treating the strip in a non-oxidizing atmosphere at 1000-1300&deg; C. for 0.5-20 hours, followed by aging treatment and grinding.

Preparation of bonded rare earth magnet-forming alloy and bonded rare earth magnet composition

A rare-earth alloy ingot is produced by melting an alloy composed of 20-30 wt % of a rare-earth constituent which is Sm alone or at least 50 wt % Sm in combination with at least one other rare-earth element, 10-45 wt % of Fe, 1-10 wt % of Cu and 0.5-5 wt % of Zr, with the balance being Co, and quenching the molten alloy in a strip casting process. The strip-cast alloy ingot has a content of 1-200 &mgr;m size equiaxed crystal grains of at least 20 vol % and a thickness of 0.05-3 mm. Rare-earth sintered magnets made from such alloys exhibit excellent magnetic properties and can be manufactured under a broad optimal temperature range during sintering and solution treatment.

Rare-earth alloy, rate-earth sintered magnet, and methods of manufacturing

Disclosed is a novel thin ribbon of a rare earth/iron/boron-based magnet alloy prepared by quenching of an alloy melt by the method of strip casting, from which a sintered permanent magnet is obtained by the powder metallurgical method. The sintered permanent magnet can be imparted with greatly improved magnetic properties or, in particular, residual magnetic flux density when the thin alloy ribbon as the base material thereof has a metallographic phase structure containing &ldquo;four-phase regions&rdquo; consisting of (a) an &agr;-iron phase, (b) a R-rich phase, in which R is a rare earth element selected from praseodymium, neodymium, terbium and dysprosium, (c) a R T B phase, in which T is iron or a combination of iron and a transition metal element other than iron and rare earth elements and x is a positive number varying with the rare earth element, and (d) a R T B phase, in which R and T each have the same meaning as defined above, each phase being dispersed with a grain diameter in a limited range, in a volume fraction of from 1 to 10%.

Quenched thin ribbon of rare earth/iron/boron-based magnet alloy

Disclosed is a thin alloy ribbon prepared by the strip casting method as an intermediate for the preparation of a sintered rare earth-based permanent magnet or, in particular, a neodymium/iron/boron-type permanent magnet. The thin alloy ribbon is characterized by a specific volume fraction of the four-phase coexisting region consisting of the &agr;-iron phase, R-rich phase, R T B phase and R T B phase each having an average grain diameter in a specified range and a specific volume fraction of the chill crystalline phase. When these requirements are satisfied, the sintered rare earth-based permanent magnet prepared from the thin alloy ribbons can be imparted with improved magnetic properties and high sintering density even without increasing the sintering temperature.

Thin ribbon of rare earth-based permanent magnet alloy

Disclosed is a thin alloy ribbon prepared by the strip casting method as an intermediate for the preparation of a sintered rare earth-based permanent magnet or in particular, a neodymium/iron/boron-type permanent magnet. The thin alloy ribbon is characterized by a specific volume fraction of the four-phase coexisting region consisting of the &agr;-iron phase, R-rich phase, R,T,B,phase and R,T,B phase each having an average grain diameter in a specified range and a specific volume fraction of the chill crystalline phase. When these requirements are satisfied, the sintered rare earth-based permanent magnet prepared from the thin alloy ribbons can be imparted with improved magnetic properties and high sintering density even without increasing the sintering temperature.

Disclosed is a novel thin ribbon of a rare earth/iron/boron-based magnet alloy prepared by quenching of an alloy melt by the method of strip casting, from which a sintered permanent magnet is obtained by the powder metallurgical method. The sintered permanent magnet can be imparted with greatly improved magnetic properties or, in particular, residual magnetic flux density when the thin alloy ribbon as the base material thereof has a metallographic phase structure containing &ldquo;four-phase regions&rdquo; consisting of (a) an &agr;-iron phase, (b) a R-rich phase, in which R is a rare earth element selected from praseodymium, neodymium, terbium and dysprosium, (c) a R,T,B,phase, in which T is iron or a combination of iron and a transition metal element other than iron and rare earth elements and x is a positive number varying with the rare earth element, and (d) a R,T,B phase, in which R and T each have the same meaning as defined above, each phase being dispersed with a grain diameter in a limited range, in a volume fraction of from 1 to 10%.

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Echizen, Japan

Takahiro Hashimoto