# US 2013/0154778 A1 · Low-neodymium, non-heavy-rare-earth and high performance magnet and preparation method

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- Number: US 2013/0154778 A1
- Document ID: US20130154778A1
- Status: Published application
- Kind: A1
- Application number: 13/711,642
- Filed: 2012-12-12
- Published: 2013-06-20
- Earliest claimed: 2011-12-15
- Assignees: Central Iron and Steel Research Institute
- Inventors: Minggang ZHU; Jingdai WANG; Wei LI; Haibo FENG; Yikun FANG; Yanfeng LI; Mingge ZHOU; Xuchao WANG; Shulin HUANG
- Web page: https://patentgrep.com/patent/US20130154778A1

## CPC

- H01F 1/015: {Metals or alloys}
- H01F 1/0573: {obtained by reduction or by hydrogen decrepitation or embrittlement}
- H01F 41/0266: {Moulding; Pressing (H01F41/0273 takes precedence; hard magnetic particles H01F1/06, H01F1/11)}
- H01F 41/0273: {Imparting anisotropy (methods and devices for magnetising permanent magnets H01F13/003)}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

The invention discloses a low-neodymium, non-heavy-rare-earth and high-performance magnet and its preparing method, and belongs to technical field of rare earth permanent magnetic material. The magnet has a chemical formula of [(Nd, Pr)100-x(Ce100-yLay)x]aFe100-a-b-cBbTMc, wherein x, y, a, b and c represent mass percents of corresponding elements respectively, 0≦x≦40%, 0≦y≦15%, 29≦a≦30%, 0.5≦b≦5%, 0.5≦c≦5%; and TM is one or more selected from Ga, Co, Cu, Nb and Al elements. A series of grades of magnets can be prepared with rapidly solidified strips of only three components. Component proportioning of magnet can also be directly performed by using mixed rare earth, so that the cost increased by further separation and purification of the rare earth is reduced. During the preparation of magnetic powder with a jet mill, an antioxidant lubricant which is composed of alcohol, gasoline and basic synthetic oil is added. A low-temperature sintering technology is adopted; and the sintering temperature is 1, 010-1, 050° C. and the annealing temperature is 450-550° C. The magnetic energy product (BH)m is more than 40 MGOe; and the coercive force Hcj is more than 10 kOe. The production time and the energy loss can be significantly reduced.

## Claims

### Claim 1

A low-neodymium, no heavy rare earth elements and high-performance magnet, its chemical formula is [(Nd, Pr)100-x (Ce100-yLay)x]aFe100-a-b-cBbTMc, wherein, x, y, a, b and c represent respectively the mass percent of the corresponding elements, and 10%≦x≦40%, 0%≦y≦15%, 29%≦a≦30%, 0.8%≦b≦1.5% and 0.5%≦c≦2%, TM is one or more selected from Ga, Co, Cu, Nb and Al.

### Claim 2 (depends on 1)

A method to prepare the low-neodymium, no heavy rare earth elements and high-performance magnet as claim 1, wherein the method comprises:
(1) preparing the raw materials respectively according to the nominal composition of Nd—Fe—B alloy in mass percent: [Nd100-x(Ce100-yLay)x]aFe100-a-b-cBbTMc (wt. %) and (Nd, Pr)aFe100-a-b-cBbTMc (wt. %), wherein 10%≦x≦40%, 0%≦y≦15%, 29%≦a≦30%, 0.8%≦b≦1.5% and 0.5%≦c≦2%; TM is one or more selected from Ga, Co, Cu, Nb and Al, the rare earth elements required can directly use the mixed rare earth with a definite proportion of components;
(2) smelting respectively the raw materials prepared in Step 1: first of all, put the raw materials into the crucible pot of an intermediate-frequency induction smelting rapid solidified furnace, switch on the power to preheat them when the vacuum reaches 10−2 Pa or above, stop the vacuum-pumping when the vacuum reaches 10−2 Pa or above again, inject the highly pure Ar to make Ar pressure inside the oven to reach −0.04˜−0.08 MPa, and then smelt; conduct the electromagnetic stirring for purification after the raw materials smelt completely, then pour the molten steel onto the water-cooled copper rollers with a linear speed of 2˜4 m/s, to obtain the rapid solidified strips with an uniform thickness of 0.1˜0.5 mm;
(3) conducting hydrogen crash for the rapid solidified strips obtained from Step 2 and get the coarse crashed magnetic powders after dehydrogenization; mix the coarse crashed magnetic powders with an anti-oxidation lubricant at a proportion of 3˜7 ml/kg by the weight of the powders under a protective atmosphere, to prevent fine particles of the powders from conglobation and oxidation in the following jet mill processing; the rotating speed of the pneumatic concentration wheel during the jet mill process is maintained at 3000 r/min˜4000 r/min, with a view to guarantee that the particle sizes of two kinds of magnetic powders are approximate, the particle sizes of the magnetic powders should be in the range of 1˜6 μm;
(4) as requirements of composition of different grades of magnets, weighing respectively the two kinds of magnetic powders prepared in Step 3 at different proportions, mix them in a mixer;
(5) under the protective atmosphere of inert gases, conducting the aligned forming for the mixed magnetic powders in a magnetic field of 1.5˜2.3 T, then conduct the cool isostatic compression processing to obtain green bodies;
(6) putting the green bodies after oriented forming and cooling isostatic compression processing into the sintering furnace with a high vacuum for sintering; heat for 0.5˜10 h at 400° C.˜800° C. for dehydrogenization during the sintering process; perform water cooling or air cooling after heating for 1˜4 h at a sintering temperature of 1000˜1050° C., and conduct the tempering treatment for 1˜4 h at 750˜950° C. and 450˜600° C., respectively.

### Claim 3 (depends on 2)

The preparation method of the said low-neodymium, no heavy rare earth elements and high-performance magnet as in claim 2, wherein the said anti-oxidation lubricant is composed of 85%-96% gasoline-alcohol and 4%-15% basic synthetic oil, the viscosity index of the basic synthetic oil adopted is more than 90, the said alcohol refers to ethanol or methanol and the said basic synthetic oil refers to a poly-a-alkene or ester oils.