Cerium-containing low-melting-point rare-earth permanent magnet liquid phase alloy and production method of permanent magnet comprising same

Abstract

The invention relates to the technical field of rare-earth permanent magnet materials, in particular to cerium-containing low-melting-point rare-earth permanent magnet liquid phase alloy, a permanent magnet comprising the liquid phase alloy and a production method of the permanent magnet. According to mass percent, the chemical formula of the liquid phase alloy is that (Cex,Nd1-x)y-Mz-Fe100-y-z, wherein 0.1<=x<=1.0, 0.04<=y<=0.9, 0<=z<=5, M is one or several of Co, Al, Cu, Ga, Nb, Mo, Ti, Zr and V. The liquid phase alloy is added in an alloy or rapid hardening mode, cerium elements entering the principal phase can be reduced and the residual magnetism can be improved by aid of scientific and reasonable composition design, the sintering temperature of the neodymium iron boron magnet can be reduced through the low-melting-point liquid phase, and therefore low-temperature sintering is achieved, and reducing of the crystal grain dimension of the magnet is benefited. The microstructure of the liquid phase is controlled through the oxygen content so that the liquid phase is ensured to be of a cerium-containing face-centered cubic structure with high coercivity, further the coercivity of the magnet is improved, and good combination property can be obtained.

Description

Technical field [0001] The invention relates to the technical field of rare earth permanent magnetic materials, and relates to a cerium-containing low-melting rare earth permanent magnetic liquid phase alloy, a magnet including the liquid phase alloy and a preparation method thereof. Background technique [0002] Sintered NdFeB is currently the permanent magnet material with the highest magnetic energy product. It is widely used in high-tech fields such as communications, medical treatment, aviation, aerospace, and electronics. It is also a key material for new energy economy such as hybrid or pure electric vehicles and wind power. Sintered NdFeB permanent magnet material is mainly composed of Nd 2 Fe 14 B is composed of the main magnetic phase, a small amount of rich phase and the neodymium-rich liquid phase between the grain boundaries. Nd 2 Fe 14 The melting point of the main magnetic phase of B is about 1185°C, and the melting point of the neodymium-rich liquid phase is 655°C...

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Problems solved by technology

However, since the above-mentioned metals are non-magnetic phases, they can only be added in a small amount, so they can only control the distribution and microstructure of the Nd-rich phase during the sintering temperature and tempering process within a small range.

[0004] On the other hand, adding rare earth elements such as lanthanum and cerium can reduce the sintering temperature, but the saturation magnetization of lanthanum iron boron and cerium iron boron phase is lower than that of neodymium iron boron phase, which reduces the remanence of the magnet, especially its anisotropy field is only It is one-third of the NdFeB phase, so the coercive force of the lanthanum and cerium magnets is very low, and the comprehensive magnetic properties are poor.

And its stability is poor, especially lanthanum and cerium are more active, and the ability to combine with oxygen is strong. The oxygen content in the magnet increases with the increase of lanthanum and cerium content.

The increase in oxygen content will cause changes in the structure of the rare earth-rich phase, resulting in a further reduction in the coercive force of the magnet, making it difficult to meet the requirements of commercial magnets for comprehensive magnetic properties such as coercive force and magnetic energy product.

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