Low-neodymium, non-heavy-rare-earth and high performance magnet

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).sub.100-x(Ce.sub.100-yLa.sub.y).sub.x].sub.aFe.sub.100-a-b-cB.sub.bTM.sub.c, wherein x, y, a, b and c represent mass percents of corresponding elements respectively, 0x40%, 0y15%, 29a30%, 0.5b5%, 0.5c5%; 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).sub.m is more than 40 MGOe; and the coercive force H.sub.cj is more than 10 kOe. The production time and the energy loss can be significantly reduced.

Claims

1. A low-neodymium, non-heavy rare earth elements and high-performance magnet having two magnetic main phases and a chemical formula of [(Nd, Pr).sub.100-x (Ce.sub.100-yLa.sub.y).sub.x].sub.aFe.sub.100-a-b-cB.sub.bTM.sub.c, wherein, x, y, a, b and c represent respectively a mass percent of the corresponding elements, 10x40, 0y15, 29a30, 0.8b1.5, 0.5c2, and TM is one or more elements selected from the group consisting of Ga, Co, Cu, Nb and Al; wherein the high-performance magnet is prepared from sintering two raw materials: [Nd.sub.100-x1(Ce.sub.100-yLa.sub.y)x.sub.1].sub.aFe.sub.100-a-b-cB.sub.bTM.sub.c and (Nd, Pr).sub.aFe.sub.100-a-b-cB.sub.bTM.sub.c, 10x140 at 1,0001,050 C. to obtain the high-performance magnet having a magnetic energy product (BH)m of more than 40 MGOe, and a coercive force Hcj of more than 10 kOe.

2. The low-neodymium, non-heavy rare earth elements and high-performance magnet of claim 1, prepared by method comprising: (1) preparing the raw materials respectively according to a nominal composition of NdFeB alloy in mass percent: [Nd.sub.100-x1(Ce.sub.100-yLa.sub.y).sub.x1].sub.aFe.sub.100-a-b-cB.sub.bTM.sub.c and (Nd, Pr).sub.aFe.sub.100-a-b-cB.sub.bTM.sub.c, wherein 10(x, x1)40, 0y15, 29a30, 0.8b1.5, 0.5c2, and TM is one or more elements selected from the group consisting of Ga, Co, Cu, Nb and Al; (2) smelting respectively the raw materials prepared in Step 1 comprising: placing one of the two raw materials into a furnace, preheating the raw material while vacuuming until the furnace reaches a vacuum of 10.sup.2 Pa or above, introducing Ar after stopping the vacuuming to provide an Ar pressure inside the furnace to 0.040.08 MPa, smelting until the raw material smelt completely conducting an electromagnetic stirring for purification after the raw material smelts completely, and pouring the molten raw material onto a cooled roller with a linear speed of 24 m/s to obtain a rapid solidified strip with an uniform thickness of 0.10.5 mm; (3) preparing powders of the raw materials respectively from the rapid solidified strip obtained from step 2 comprising: conducting a hydrogen crash to the rapid solidified strip obtained from Step 2 to obtain a coarse crashed magnetic powder after dehydrogenization, mixing the coarse crashed magnetic powder with an anti-oxidation lubricant at a proportion of 37 ml/kg by the weight of the powder under a protective atmosphere to provide a first mixture, processing the first mixture in a jet mill process at a rotating speed of a pneumatic concentration wheel of 3,000 r/min4,000 r/min to obtain particles of the raw material with particle sizes in the range of 16 m; (4) mixing the powders of the two raw materials prepared in Step 3 at a desired proportion to provide mixed magnetic powders; (5) under a protective atmosphere of inert gases, conducting an aligned forming for the mixed magnetic powders in a magnetic field of 1.52.3 T, then conducting a cool isostatic compression processing to obtain green bodies; and (6) putting the green bodies after oriented forming and cool isostatic compression processing into the sintering furnace with a high vacuum for sintering heating for 0.510 h at 400 C.800 C. for dehydrogenization during a sintering process; cooling after heating for 14 h at a sintering temperature of 1,0001,050 C., and conducting a tempering treatment for 14 h at 750950 C. and 450600 C., respectively.

3. The low-neodymium, non-heavy rare earth elements and high-performance magnet of claim 2, wherein the anti-oxidation lubricant comprises 85%-96% gasoline-alcohol and 4%-15% basic synthetic oil, wherein a viscosity index of the basic synthetic oil is more than 90, the alcohol is ethanol or methanol, and the basic synthetic oil is a poly-a-alkene or an ester oil.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic drawing of the microstructure of the magnet prepared by present invention. Ce, La (single one of them, or the combination of them) distribute mainly in the grain-boundary phase. Nd.sub.2Fe.sub.14B still maintains a higher volume fraction in the main phase.

(2) FIG. 2 shows the main phase energy spectrum drawing of magnet in embodiment 3 of present invention.

(3) FIG. 3 shows the main phase energy spectrum drawing of magnet in embodiment 3 of present invention.

DETAILED DESCRIPTION OF THE EMBODIMENT MODES

(4) Below are detailed descriptions of the embodiments based upon the technical solution of this invention, which are helpful to better understand of this invention. But, it is worthy of mentioning that the embodiments below are provided for the sole purpose of explanation only, and the protection scope of this invention is not limited to the embodiments below.

Embodiment 1

(5) As designed component (Nd.sub.90Ce.sub.10).sub.30Fe.sub.bal B.sub.0.94TM.sub.0.67 (TM=Ga, Co, Cu, Nb), wherein 10% Nd is substituted by Ce.

(6) Step 1: prepare the raw materials respectively as the nominal composition of NdFeB alloy in mass percent: (Nd.sub.70Ce.sub.30).sub.30Fe.sub.bal B.sub.0.94TM.sub.0.67 (TM=Ga, Co, Cu, Nb) and Nd.sub.30Fe.sub.balB.sub.0.94 TM.sub.0.67 (TM=Ga, Co, Cu, Nb);

(7) Step 2: smelt respectively the prepared raw materials with two different compositions. 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.sup.2 Pa or above, stop the vacuum-pumping when the vacuum reaches 10.sup.2 Pa or above again, inject the highly pure Ar to make Ar pressure inside the furnace reach 0.06 MPa, and then smelt; conduct the electromagnetic stirring for purification after the raw materials smelt completely, finally, pour the molten steel onto the water-cooled copper rollers with a linear speed of 3 m/s, to get the rapidly solidified strips with a uniform thickness of 0.3 mm;

(8) Step 3: put the obtained two kinds of rapidly solidified strips into hydrogenation furnace respectively to conduct coarse crash; mix the anti-oxidation lubricant and the coarse crashed magnetic-particles at a proportion of 5 ml/kg under the protective atmospheres. The gasoline-alcohol in the anti-oxidation lubricant takes 90% and eighteen alkyl acid ester of glycerol takes 10%; then conduct jet milling respectively, the rotating speed of the pneumatic concentration wheel in the following jet milling process is controlled at 3100 r/min, with a view to guarantee that the particle sizes of two kinds of magnetic powders are approximate. The uniform particle sizes of the magnetic-particles shall be approximately 3 m;

(9) Step 4: mix the two kinds of magnetic powders prepared in Step 3 as the designed composition requirements, wherein the amount of the magnetic powders with the nominal composition of (Nd.sub.70Ce.sub.30).sub.30Fe.sub.bal B.sub.0.94TM.sub.0.67 (TM=Ga, Co, Cu, and Nb) will be of the total amount of the two kinds of magnetic powders; mix the two kinds of magnetic powders sufficiently in a mixer;

(10) Step 5: under the protective atmosphere of inert gases, conduct the aligned forming for the mixed magnetic powders in a magnetic field with an intensity of 2 T, then conduct the cool isostatic compression processing to obtain green body;

(11) Step 6: put the formed green bodies into a high vacuum sintering furnace; heat for 1 h at temperature of 400 C., 600 C. and 800 C. for dehydrogenization; water cooling after sintering for 2 h at 1020 C., and conduct the tempering treatment for 2 h at 900 C. and 520 C., respectively.

(12) NIM-2000HF rare earth permanent magnet measuring device is adopted to measure the magnetic properties of the magnets. The measured properties are shown in Table 1 below.

(13) TABLE-US-00001 TABLE 1 Nominal composition B.sub.r/kGs H.sub.cj/kOe (BH).sub.m/MGOe (Nd.sub.90Ce.sub.10).sub.30Fe.sub.balB.sub.0.94TM.sub.0.67 13.95 12.19 46.63 (Ga, Co, Cu, Nb)

Embodiment 2

(14) As designed composition (Nd.sub.85Ce.sub.15).sub.30Fe.sub.balB.sub.0.94TM.sub.0.67 (TM=Ga, Co, Cu, and Nb), 15% Nd is substituted by Ce.

(15) Step 1: prepare the raw materials respectively as the nominal composition of NdFeB alloy in mass percent: (Nd.sub.70Ce.sub.30).sub.30Fe.sub.balB.sub.0.94TM.sub.0.67 (TM=Ga, Co, Cu, and Nb) and Nd.sub.30Fe.sub.balB.sub.0.94 TM.sub.0.67 (TM=Ga, Co, Cu, and Nb);

(16) Step 2: smelt respectively the raw materials. 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.sup.2 Pa or above, stop the vacuum-pumping when the vacuum reaches 10.sup.2 Pa or above again, inject the highly pure Ar to make Ar pressure inside the furnace reach 0.06 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 3 m/s, to get the rapid solidified strips with a uniform thickness of 0.3 mm;

(17) Step 3: conduct hydrogen crash for the two kinds of rapid solidified strips obtained and get the coarse crashed magnetic powder after dehydrogenization; mix the anti-oxidation lubricant and the coarse decrepitated magnetic powders at a proportion of 5 ml/kg under an protective atmosphere, wherein the gasoline-methanol in the anti-oxidation lubricant takes 90% and eighteen alkyl acid ester of glycerol takes 10%. In the following jet milling process conducted for them respectively, the rotating speed of the pneumatic concentration wheel in the jet mill processing is controlled at 3100 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 prepared shall be approximately 3 m;

(18) Step 4: mix the two kinds of magnetic powders prepared in Step 3 as the design composition required, and the amount of the magnetic powder with the nominal composition of (Nd.sub.70Ce.sub.30).sub.30Fe.sub.bal B.sub.0.94TM.sub.0.67 (TM=Ga, Co, Cu, and Nb) will be of the total amount of the two kinds of magnetic powders; mix the two kinds of magnetic powders sufficiently in a mixer;

(19) Step 5: under the protective atmosphere of inert gases, conduct the aligned forming for the mixed magnetic powders in a magnetic field with an intensity of 2 T, then conduct the cool isostatic compression processing to obtain green body;

(20) Step 6: put the green bodies prepared in Step 5 into the sintering furnace with a high vacuum for sintering; heat for 1 h at 400 C., 600 C. and 800 C. for dehydrogenization during the sintering process; water cooling shall be conducted after sintering for 2 h at 1020 C., and conduct the tempering treatment for 2 h at 900 C. and 520 C., respectively;

(21) NIM-2000HF rare earth permanent magnet measuring device is adopted to measure the magnetic properties of the magnets. The measured properties are shown in the Table 2 below.

(22) TABLE-US-00002 TABLE 2 Nominal composition B.sub.r/kGs H.sub.cj/kOe (BH).sub.m/MGOe (Nd.sub.85Ce.sub.15).sub.30Fe.sub.balB.sub.0.94TM.sub.0.67 13.76 11.39 45.58 (TM = Ga, Co, Cu, Nb)

Embodiment 3

(23) As the designed composition (Nd.sub.80Ce.sub.20).sub.30Fe.sub.bal B.sub.0.94TM.sub.0.67 (TM=Ga, Co, Cu, and Nb), 20% Nd is substituted by Ce.

(24) Step 1: prepare the raw materials respectively as the nominal composition of (Nd.sub.70Ce.sub.30).sub.30Fe.sub.bal B.sub.0.94TM.sub.0.67 (TM=Ga, Co, Cu, Nb) and Nd.sub.30Fe.sub.balB.sub.0.94 TM.sub.0.67 (TM=Ga, Co, Cu, and Nb);

(25) Step 2: smelt respectively the raw materials. 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.sup.2 Pa or above, stop the vacuum-pumping when the vacuum reaches 10.sup.2 Pa or above again, inject the highly pure Ar to make Ar pressure inside the furnace reach 0.06 MPa, and smelt then; 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 3 m/s, to obtained the rapid solidified strips with a uniform thickness of 0.3 mm;

(26) Step 3: conduct hydrogen crash for the two kinds of rapid solidified strips obtained and get the coarse crashed magnetic powders after dehydrogenization; mix the anti-oxidation lubricant and the coarse crashed magnetic powders at a proportion of 5 ml/kg under the protective atmosphere. The gasoline-methanol in the anti-oxidation lubricant takes 90% and eighteen alkyl acid ester of glycerol takes 10%. In the following jet milling process conducted for them respectively, the rotating speed of the pneumatic concentration wheel shall be controlled at 3100 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 prepared shall be approximately 3 m;

(27) Step 4: mix the two kinds of magnetic powder prepared in Step 3 as the designed composition required, and the amount of the magnetic powders with the nominal composition of (Nd.sub.70Ce.sub.30).sub.30Fe.sub.bal B.sub.0.94TM.sub.0.67 (TM=Ga, Co, Cu, and Nb) account for of the total amount of the two kinds of magnetic powders; mix the two kinds of magnetic powers sufficiently in a mixer;

(28) Step 5: under the protective atmosphere of inert gases, conduct the aligned forming for the mixed magnetic powders in a magnetic field with an intensity of 2 T, then conduct the cool isostatic compression processing to obtain green body;

(29) Step 6: put the green bodies prepared in Step 5 into the sintering furnace with a high vacuum for sintering; heat for 1 h at 400 C., 600 C. and 800 C. for dehydrogenization during the sintering process; water cooling shall be conducted after sintering for 2 h at 1020 C., and conduct the tempering treatment for 2 h respectively at 900 C. and 520 C.;

(30) NIM-2000HF rare earth permanent magnet measuring device is adopted to measure the magnetic properties of the magnets. The measured properties are shown in the Table 3 below.

(31) TABLE-US-00003 TABLE 3 Nominal composition B.sub.r/kGs H.sub.cj/kOe (BH).sub.m/MGOe (Nd.sub.80Ce.sub.20).sub.30Fe.sub.balB.sub.0.94TM.sub.0.67 13.61 11.12 44.31 (TM = Ga, Co, Cu, Nb)