In recent years, normally used high-temperature stability permanent magnetic material mainly is the RCo in alnico alloy and the rare-earths-cobalt, type (R is rare earth elements such as Sm, Ce), R
2(Co, Cu, Fe, M)
17Type (M is metallic elements such as Ti, Zr, Hf), its open circuit magnetic strength temperature coefficient less than-0.04%/℃, but the maximum magnetic energy product of alnico generally is lower than 12MGOe, the maximum magnetic energy product of rare earth cobalt alloy is difficult to be higher than 30MGOe; And Sm, Co raw material are poor to be lacked, and the price of Al, Ni, Sm, Co was jumped and risen recent years, so its unit magnetic energy cost is very high.
The NdFeB permanent magnet of invention in 83 years, its main magnetic is R mutually
2Fe
14Type B four directions phase, the laboratory magnetic energy product can reach 50MGOe, only 310 ℃ of Curie points, temperature coefficient up to 0.126%/℃, and serviceability temperature is lower than 100 ℃, is difficult to precision instrumentation and magneto (for example Chinese patent application CN85101455A).Though later on the temperature coefficient of magnet improves to some extent, magnetic energy product is 25~35MGOe, the magnetic strength temperature coefficient still has-0.05%/℃, and cost amplification is bigger.
At the beginning of the end of the year to 86 85, a day disclosure is speciallyyed permit clear 60-244003, clear 61-10209 and is successively disclosed with RFe, for the temperature coefficient of principal phase be-0.03%/℃, magnetic energy product is the low-temperature coefficient NdFe alloy about 30MGOe, its B content<2%.
The objective of the invention is to overcome the shortcoming of above-mentioned prior art, obtain the big and rare earth iron Co-Mo permanent magnet with low cost of a kind of new type low temperature degree coefficient, serviceability temperature height, magnetic energy product.
For achieving the above object, the present invention is achieved in that the present invention improves on the composition basis of the conventional NdFeBCo permanent-magnet alloy of CN85101455A, adds Cu or Cu and other alloying element, promotes 1-5 type magnetic to compare multiform, makes R
2Fe
14The Type B four directions exists when identical with the 1-5 type mutually, containing heavy rare earth element more after a little while, when particularly adding the M element, it has positive magnetic strength temperature coefficient, the magnetic property of alloy still very high (being not less than 25MGOe), but the magnetic strength temperature coefficient can drop to-0.02% very soon/℃ below.
Key of the present invention is: the composition scope of this permanent magnet is (atomic percent): 5~20% R, R is the interpolation general name (containing a kind of light rare earth at least) of La, Ce, Pr, Nd, Sm, six light rare earth element of Pm, 0.1~10% R ', R ' is the interpolation general name (containing a kind of heavy rare earth at least) of Gd, Dy, Y, Eu, Ho, Tb, Er, Tm, Yb, ten heavy rare earth elements of Lu, 5~35% Co, 1~15% B, 0.01~10% Cu, all the other are Fe and unavoidable impurities.
As extending of aforementioned composition, another viewpoint of the present invention is, further add the M element, the composition scope of alloy is (atomic percent): 5~20% R, R is La, Ce, Pr, Nd, Sm, the interpolation general name of six light rare earth element of Pm (containing a kind of light rare earth at least), 0.1~10% R ', R ' is Gd, Dy, Y, Eu, Ho, Tb, Er, Tm, yb, the interpolation general name of ten heavy rare earth elements of Lu (containing a kind of heavy rare earth at least), 5~35% Co, 1~15% B, 0.01~10% Cu, M less than 10%, M are Nb, Al, Ge, Ti, Zr, Hf, Ga, Ta, W, Mo, the interpolation general name of Sb (containing a kind of at least).
The main magnetic of permanent magnet of the present invention is by R
2Fe
14Type B four directions phase and R ' (Co, Cu)
5Type constitutes mutually jointly.Found in the past in containing heavy rare earth element NdFeCoB alloy for a long time, R ' Co to occur
5The type phase, because the heavy rare earth element price is very expensive, thereby cost increases a lot, simultaneously, ferrimagnetism coupling between heavy rare earth element and transition elements Fe, the Co makes alloy have positive temperature coefficient, but causes the rapid reduction of the alloy magnetization, Co inserts the soft magnetism phase Nd(Fe that grows nonparasitically upon another plant, Co)
2Cause the coercitive obvious deterioration of alloy, so the magnetic property of alloy is very low, at this moment, though because R ' Co
5Have positive temperature coefficient mutually and can certain compensation be arranged, but this compensation has not had practical value the mutually high negative temperature coefficient in four directions.
The present invention causes alloy containing heavy rare earth element more after a little while owing to added the Cu element in alloy, has promoted R ' (Co, Cu)
5The more formation of phase, R ' (Co, Cu)
5Has positive temperature coefficient mutually, compensation effect to the alloy temperature coefficient is more obvious, simultaneously, because the 1-5 type is when increasing mutually, this moment, to contain R ' in mutually less in the four directions, the four directions keeps very high magnetic energy mutually, like this, temperature coefficient is decided by the compensation of 1-5 type phase in alloy, and magnetic property is decided mutually by the four directions that accounts for the volume overwhelming majority again, when containing the M element especially in alloy, the M element has suppressed Nd(Fe, Co)
2The formation of soft magnetism phase causes alloy to have the excellent magnetism energy having under high-curie temperature, low-temperature coefficient, low cost, the high serviceability temperature condition.
R ' and Co element are the essential elementss that makes the alloy magnetic property produce temperature-compensating, have excellent temperature stability.The effect of Cu element is to promote R ' and Co element R ' formed more (Co, Cu)
5The type phase reduces at R
2Fe
14The middle mutually R ' content in Type B four directions, thus in the maintenance good temperature characteristics, improve the magnetic property of alloy, and reduce cost.The M element is the effective element that improves the alloy coercive force, improves the alloy serviceability temperature.
The common production technology of low-temperature coefficient permanent magnet of the present invention is: alloy composition is prepared burden on request, melt becomes alloy pig in consumable, non-consumable arc furnace or induction furnace, alloy pig is carried out fragmentation with jaw crusher, pulverizer for laboratory test, ball mill or air-flow grinding machine, particle size should be at 1~20 μ m, the gained powder carries out directed compression moulding in>15KOe magnetic field, formed body is sintering in vacuum or inert atmosphere, sintering temperature is at 900~1200 ℃, and the cooling rate with 0.5~1000 ℃/min behind the sintering is chilled to room temperature.
Determine whether the needs temper according to different components behind the sintering, treatment temperature is 400~1000 ℃ of scopes.
The form of permanent magnet of the present invention can have following a few class:
Except sintered magnet with the directed compacting of powder metallurgic method, also have the alloy pulverizing back with organic binder cemented binding magnet, the alloy binding magnet that hot compression forms behind fast quenching, the sintering or the binding magnet that utilize CaO to make by reduction-diffusion process as reducing agent, wherein ideal with the magnetic property of sintered magnet.
Can obtain a kind of novel permanent magnetic body according to the present invention, its Curie temperature is higher than 500 ℃, and maximum magnetic energy product is greater than 25MGOe, and temperature coefficient is lower than-0.02%/℃ (vibrating specimen magnetometer measurement).
The present invention is owing to only used a spot of heavy rare earth element, the MGOe of its unit cost is far below SmCo and AlNiCo permanent magnet, temperature characterisitic and SmCo, AlNiCo are suitable, magnetic property is apparently higher than SmCo, AlNiCo permanent magnet, very possible AlNiCo, the SmCo permanent magnet of replacing is suitable for requirement high-performance, low-temperature coefficient, wide spectrum cheaply.