Shin-etsu Chemical Co., Ltd.

Lintec Corporation

Koichi Hirota

Hajime Nakamura

Takehisa Minowa

Tetsuya Kume

Tetsuya Ohashi

Koji Miyata

Kenji Yamamoto

Takahiro Hashimoto

Koji Sato

Yuhito Doi

Hiroaki Nagata

Masanobu Shimao

Masayuki Kamata

Masakatsu Honshima

Mikio Yoshida

Hiroki Iida

Junya Fukuda

Naoki Watanabe

Tadao Nomura

Takanori Saito

Kazuaki Sakaki

Kazuhiro Kon

Masao Kogure

Kazuya Fukui

Michihiro Oida

Yuuji Gouki

Akihiro Yoshinari

Akira Yamada

A rare earth sintered magnet is manufactured by preparing a R-T-X sintered body having a major phase of RTX composition wherein Ris a rare earth element(s) and essentially contains Pr and/or Nd, T is Fe, Co, Al, Ga, and/or Cu, and essentially contains Fe, and X is boron and/or carbon, forming an alloy powder containing 5≤R≤60, 5≤M≤70, and 20<B≤70, in at %, wherein Ris a rare earth element(s) and essentially contains Dy and/or Tb, M is Fe, Cu, Al, Co, Mn, Ni, Sn, and/or Si, and B is boron, disposing the alloy powder on the sintered body, and heat treating the alloy-covered sintered body.

Method for manufacturing rare earth sintered magnet

Provided is an R—Fe—B-based sintered magnet which has a composition comprising R (wherein R represents at least one element selected from rare earth elements, and essentially contains Nd), B, M (wherein M represents at least one element selected from Si, Al, Mn, Ni, Co, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb and Bi), X (wherein X represents at least one element selected from Ti, Zr, Hf, Nb, V and Ta) and C, with a remainder comprising Fe, O and unavoidable impurities, and has a main phase comprising RFeB and a grain boundary phase comprising an R—C phase having a higher R concentration and a higher C concentration than those in the main phase, the R—Fe—B-based sintered magnet being characterized in that the area ratio of the R—C phase in a cross section of the magnet is more than 0% and 0.5% or less.

R—Fe—B-based sintered magnet

Provided is a magnetic refrigeration material whose magnetic transition temperature has been adjusted with high accuracy and which includes at least a first predetermined magnetic refrigeration material and a second predetermined magnetic refrigeration material which differs from the first magnetic refrigeration material. The absolute value of the difference between the magnetic transition temperature of the present magnetic refrigeration material and a target magnetic transition temperature is 0.7 K or less. The content of the first magnetic refrigeration material and the content of the second magnetic refrigeration material are determined by the magnetic transition temperatures of the first magnetic refrigeration material and the second magnetic refrigeration material and by a target magnetic transition temperature of the magnetic refrigeration material.

Method for producing magnetic refrigeration material, and magnetic refrigeration material

There are provided a method for producing a magnetic refrigeration material whose magnetic transition temperature can be adjusted with high accuracy, and a magnetic refrigeration material whose magnetic transition temperature has been adjusted with high accuracy. The magnetic refrigeration material production method of the present invention includes the steps of: preparing a first predetermined magnetic refrigeration material and a second predetermined magnetic refrigeration material which differs from the first magnetic refrigeration material; and mixing the first magnetic refrigeration material and the second magnetic refrigeration material to obtain a third magnetic refrigeration material. The content of the first magnetic refrigeration material and the content of the second magnetic refrigeration material in the third magnetic refrigeration material are determined by the magnetic transition temperatures of the first magnetic refrigeration material and the second magnetic refrigeration material and by a target magnetic transition temperature of the third magnetic refrigeration material. The magnetic refrigeration material of the present invention includes at least a first predetermined magnetic refrigeration material and a second predetermined magnetic refrigeration material which differs from the first magnetic refrigeration material. The absolute value of the difference between the magnetic transition temperature of the present magnetic refrigeration material and a target magnetic transition temperature is 0.7 K or less.

Provided is a rare earth sintered magnet in which a multi-layer main phase particle having multiple layers including a layer 1 having Rconcentration, represented by at %, higher than that of a center of the particle, a layer 2 which is formed on the outside of the layer 1 and has Rconcentration lower than that of the layer 1, and a layer 3 which is formed on the outside of the layer 2 and has Rconcentration higher than that of the layer 2 is present at least in a portion in the vicinity of a surface of the main phase particle within at least 500 &#x3bc;m from a surface of the sintered magnet body.

Rare earth sintered magnet

R&#x2014;Fe&#x2014;B sintered magnet has a main phase containing R(Fe,(Co))B intermetallic compound and a grain boundary phase. The inter-particle grain boundary includes an expanded width part that is surrounded by a narrow width part at which the inter-particle width is 10 nm or less and that has a structure distended in the inter-particle width direction as compared with the grain boundary width of the narrow width part; the inter-particle width at the expanded width part is at least 30 nm; Fe/R ratio in the expanded width part is 0.01-2.5; the main phase includes, in the surface part thereof, an HR-rich phase represented by (R',HR)(Fe,(Co))B (R&#x2032; represents rare-earth elements excluding Dy, Tb, and Ho, and that essentially include Nd; and HR represents Dy, Tb, and Ho); the contained amount of HR in the HR-rich phase is higher than that in the central part of the main phase.

R&#x2014;Fe&#x2014;B sintered magnet and production method therefor

An R&#x2014;Fe&#x2014;B base sintered magnet is provided comprising a main phase containing an HR rich phase of (R',HR)(Fe,(Co))B wherein R&#x2032; is an element selected from yttrium and rare earth elements exclusive of Dy, Tb and Ho, and essentially contains Nd, and HR is an element selected from Dy, Tb and Ho, and a grain boundary phase containing a (R&#x2032;,HR)&#x2014;Fe(Co)-Mphase in the form of an amorphous phase and/or nanocrystalline phase, the (R&#x2032;,HR)&#x2014;Fe(Co)-Mphase consisting essentially of 25-35 at % of (R&#x2032;,HR), 2-8 at % of Mwhich is at least one element selected from Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, up to 8 at % of Co, and the balance of Fe. The HR rich phase has a higher HR content than the HR content of the main phase at its center. The magnet produces a high coercivity despite a low content of Dy, Tb and Ho.

R-Fe-B sintered magnet

An R&#x2014;Fe&#x2014;B base sintered magnet is provided consisting essentially of R (which is at least two rare earth elements and essentially contains Nd and Pr), Mwhich is at least two of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, Mwhich is at least one of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, boron, and the balance of Fe, and containing an intermetallic compound R(Fe,(Co))B as a main phase. The magnet contains an R&#x2014;Fe(Co)-Mphase as a grain boundary phase, the R&#x2014;Fe(Co)-Mphase contains A phase which is crystalline with crystallites of at least 10 nm formed at grain boundary triple junctions, and B phase which is amorphous and/or nanocrystalline with crystallites of less than 10 nm formed at intergranular grain boundaries and optionally grain boundary triple junctions.

R-Fe-B sintered magnet and making method

An R&#x2014;Fe&#x2014;B base sintered magnet is prepared through the steps of providing an alloy fine powder having a predetermined composition, compression shaping the alloy fine powder in an applied magnetic field into a compact, sintering the compact at a temperature of 900-1,250&#xb0; C. into a sintered body, cooling the sintered body to 400&#xb0; C. or below, high-temperature heat treatment including placing a metal, compound or intermetallic compound containing HR which is Dy, Tb and/or Ho, on the surface of the sintered body, heating at a temperature from more than 950&#xb0; C. to 1,100&#xb0; C., for causing grain boundary diffusion of HR into the sintered body, and cooling to 400&#xb0; C. or below, and low-temperature heat treatment including heating at a temperature of 400-600&#xb0; C. and cooling to 300&#xb0; C. or below. The sintered magnet produces a high coercivity despite a low content of Dy, Tb and Ho.

Method for preparing R&#x2014;Fe&#x2014;B sintered magnet

An R&#x2014;Fe&#x2014;B base sintered magnet is provided comprising a main phase containing an HR rich phase of (R', HR)(Fe,(Co))B wherein R&#x2032; is an element selected from yttrium and rare earth elements exclusive of Dy, Tb and Ho, and essentially contains Nd, and HR is an element selected from Dy, Tb and Ho, and a grain boundary phase containing a (R&#x2032;, HR)&#x2014;Fe(Co)-Mphase in the form of an amorphous phase and/or nanocrystalline phase, the (R&#x2032;, HR)&#x2014;Fe(Co)-Mphase consisting essentially of 25-35 at % of (R&#x2032;, HR), 2-8 at % of Mwhich is at least one element selected from Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, up to 8 at % of Co, and the balance of Fe. The HR rich phase has a higher HR content than the HR content of the main phase at its center. The magnet produces a high coercivity despite a low content of Dy, Tb and Ho.

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

The invention provides an R&#x2014;Fe&#x2014;B sintered magnet consisting essentially of 12-17 at % of Nd, Pr and R, 0.1-3 at % of M, 0.05-0.5 at % of M, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R(Fe,(Co))B intermetallic compound as a main phase, and having a core/shell structure that the main phase is covered with a grain boundary phases. The sintered magnet has an average grain size of less than 6 &#x3bc;m, a crystal orientation of more than 98%, and a degree of magnetization of more than 96%, and exhibits a coercivity of at least 10 kOe despite a low or nil content of Dy, Tb, and Ho.

The invention provides an R&#x2014;Fe&#x2014;B sintered magnet consisting essentially of 12-17 at % of Nd, Pr and R, 0.1-3 at % of M, 0.05-0.5 at % of M, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R(Fe,(Co))B intermetallic compound as a main phase, and having a core/shell structure that the main phase is covered with grain boundary phases. The sintered magnet exhibits a coercivity of at least 10 kOe despite a low or nil content of Dy, Tb and Ho.

R&#x2014;Fe&#x2014;B sintered magnet and making method

A rare earth sintered magnet is an anisotropic sintered body comprising NdFeB crystal phase as primary phase and having the composition RTMSiBwherein Ris a rare earth element inclusive of Sc and Y, T is Fe and/or Co, M is Al, Cu, Zn, In, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, or W, 'a' to 'e' are 12&#x2264;a&#x2264;17, 0&#x2264;c&#x2264;10, 0.3&#x2264;d&#x2264;7, 5&#x2264;e&#x2264;10, and the balance of b, wherein Dy and/or Tb is diffused into the sintered body from its surface.

Rare earth sintered magnet and making method

A sintered Nd base magnet segment has a coercive force high at the periphery and lower toward the inside. A method for preparing the magnet includes the steps of: (a) providing a sintered Nd base magnet block having surfaces and a magnetization direction, (b) coating the surfaces of the magnet block excluding the surface perpendicular to the magnetization direction with a Dy or Tb oxide powder, a Dy or Tb fluoride powder, or a Dy or Tb-containing alloy powder, (c) treating the coated block at a high temperature for causing Dy or Tb to diffuse into the block, and (d) cutting the block in a plane perpendicular to the magnetization direction into a magnet segment having a coercive force distribution on the cut section that the coercive force is high at the periphery and lower toward the inside and a constant coercive force distribution in the magnetization direction.

Growing community of inventors

Echizen, Japan

Koichi Hirota