The magnet material is represented by a composition formula 1: (R.sub.1-xY.sub.x).sub.aM.sub.bA.sub.c, where R is at least one element selected from the group consisting of rare-earth elements, M is at least one element selected from the group consisting of Fe and Co, A is at least one element selected from the group consisting of N, C, B, H and P, x is a number satisfying 0.01≤x≤0.8, a is a number satisfying 4≤a≤20 atomic %, b is a number satisfying b=100−a−c atomic %, and c is a number satisfying 0≤c≤18 atomic %), and includes a main phase having a Th.sub.2Ni.sub.17 crystal structure. A concentration of the element M in the main phase is 89.6 atomic % or more.

A two-step diffusion method for preparing high-performance dual-main-phase sintered mischmetal-iron-boron magnet belongs to the preparing technical field of rare earth permanent magnet materials. The compositions of the two main phase alloys are RE-Fe—B (RE is Nd or Pr) and (Nd, MM)-Fe—B (MM is mischmetal), respectively. First, PrHoFe strip-casting alloy is used as a diffusion source. Next, a PrHo-rich layer is uniformly coated on the surface of (Nd, MM)-Fe—B hydrogen decrepitation powders. The higher anisotropic fields of Pr.sub.2Fe.sub.14B and Ho.sub.2Fe.sub.14B are used to improve the coercivity. Then, the ZrCu strip-casting alloy is used as a diffusion source. A Zr-rich layer is uniformly coated on the surface of the powders after the first-step diffusion, which prevents the growth of the MM-rich main phase grains during the sintering process and the inter-diffusion between the two main phases, thus obtains high coercivity.

A motor comprising: (a) one or more motor stators including a plurality of motor windings; (b) a roller shaft connected to the one or more motor stators, the roller shaft extending along a longitudinal axis of the motor and being adapted to span between two frame members; and (c) a motor rotor including: (i) a roller tube including a key, a key recess, or both, and (ii) one or more ring magnets having: (1) a mating surface shaped to substantially mate to a mating surface of the roller tube and (2) a key recess that receives the key of the roller tube, that receives a separate key that extends into the key recess of one of the one or more ring magnets and the key recess, or both; wherein the one or more ring magnets are produced from a rare earth metal; and wherein the motor rotor carries a load of an article so that the article is moved by the motor rotor.

In at least one embodiment, a single sintered magnet is provided having a concentration profile of heavy rare-earth (HRE) elements within a continuously sintered rare-earth (RE) magnet bulk. The concentration profile may include at least one local maximum of HRE element concentration within the bulk such that a coercivity profile of the magnet has at least one local maximum within the bulk. The magnet may be formed by introducing alternating layers of an HRE containing material and a magnetic powder into a mold, pressing the layers into a green compact, and sintering the green compact to form a single, unitary magnet.

This invention is directed to a corrosion resistant permanent magnet, to a method for producing a corrosion resistant permanent magnet, and to an intravascular blood pump comprising the magnet. The magnet is corrosion resistant due to a composite coating comprising a metal layer, optionally a metal oxide layer, a layer formed from poly(2-chloro-p-xylylene), and a linker layer between the metal oxide layer and the poly(2-chloro-p-xylylene) layer.

A sintered annular magnet with a radial orientation of a remanent magnetic field, including: a principal annular part made from a ferromagnetic material, that has a first degree of magnetic anisotropy in the radial direction; and an annular reinforcing part fixed to the principal part of the magnet, the reinforcing part being made from same ferromagnetic material as the ferromagnetic material forming the principal part, and that has a second degree of magnetic anisotropy in the radial direction, the first degree being higher than the second degree.

Provided is a sintered magnet that is an R-T-B based sintered magnet having a region having a concentration of at least one heavy rare earth element decreasing from the surface toward the inside, in which the at least one heavy rare earth element includes at least either of Tb or Dy, R includes Nd, T includes Fe, Co, and Cu, there is a grain boundary phase containing at least either of Tb or Dy and Nd between two main phase particles, and a value obtained by subtracting a half value width of a concentration distribution curve of Cu from a half value width of a concentration distribution curve of Tb or Dy in a part including the grain boundary phase is from 10 to 20 nm.

A sintered R.sub.2M.sub.17 magnet is provided that comprises at least 70 Vol % of a Sm.sub.2M.sub.17 phase, wherein R is at least one of the group consisting of Ce, La, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yt, Lu and Y, and M comprises Co, Fe, Cu and Zr. In an area of the R.sub.2M.sub.17 sintered magnet of 200 by 200 μm viewed in a Kerr micrograph, an areal proportion of demagnetised regions after application of an internal opposing field of 1200 kA/m is less than 5% or less than 2%.

A sintered ferrite magnet comprising (a) a ferrite phase having a hexagonal M-type magnetoplumbite structure comprising Ca, an element R which is at least one of rare earth elements and indispensably includes La, an element A which is Ba and/or Sr, Fe, and Co as indispensable elements, the composition of metal elements of Ca, R, A, Fe and Co being represented by the general formula of Ca.sub.1-x-yR.sub.xA.sub.yFe.sub.2n-zCo.sub.z, wherein the atomic ratios (1-x-y), x, y and z of these elements and the molar ratio n meet the relations of 0.3≦(1-x-y)≦0.65, 0.2≦x≦0.65, 0≦y≦0.2, 0.03≦z≦0.65, and 4≦n≦7, and (b) a grain boundary phase indispensably containing Si, the amount of Si being more than 1% by mass and 1.8% or less by mass (calculated as SiO.sub.2) based on the entire sintered ferrite magnet, and its production method.

In an embodiment, a permanent magnet includes a composition represented by a composition formula: R(Fe.sub.pM.sub.qCu.sub.r(Co.sub.1-sA.sub.s).sub.1-p-q-r).sub.z, where, R is at least one element selected from rare earth elements, M is at least one element selected from Ti, Zr, and Hf, A is at least one element selected from Ni, V, Cr, Mn, Al, Si, Ga, Nb, Ta, and W, 0.05≦p≦0.6, 0.005≦q≦0.1, 0.01≦r≦0.15, 0≦s≦0.2, and 4≦z≦9, and a two-phase structure of a Th.sub.2Zn.sub.17 crystal phase and a copper-rich phase. In a cross-section of the permanent magnet containing a crystal c axis of the Th.sub.2Zn.sub.17 crystal phase, an average distance between the copper-rich phases is 120 nm or less.