【作者】 杨凯；

【导师】 韩培德； 高峰； 衣晓飞；

【作者基本信息】 太原理工大学 ， 材料工程（专业学位）， 2022， 硕士

【摘要】 烧结钕铁硼作为第三代稀土永磁材料,因其秉承的优异磁性能而被广泛应用于新能源汽车、智能制造以及医疗等高新行业领域。但是随着不同行业内的需求及产量的不断增加,主要原材料价格屡创新高,且对磁体的矫顽力以及热稳定性也有着越来越高的要求。目前,工业中常采用在熔炼时直接添加重稀土元素镝或铽来提升磁体的矫顽力,制备高综合性能钕铁硼磁体。但是该方法重稀土的利用率低,生产成本高,剩磁和磁能积下降幅度大。为此本文一方面通过设计成分在其中加入价格更低,丰度更高的Gd元素制造出性能优异价格低廉的烧结Nd Fe B磁体,另一方面通过调整磁控溅射基体材料的结构,以提高扩散效率为基础,为稀土元素的合理综合利用提供了一种新的思路,主要研究内容如下:（1）通过调整（Pr,Nd）_31-xGd_x Fe_balAl_0.4Cu_0.2Ga_0.2Zr_0.2Co₁B_0.9磁体中Gd元素含量,分析了Gd对磁体磁性能、温度稳定性的影响,通过SEM和XRD表征方法,研究了Gd的添加对其微观结构的影响。随着磁体中Gd元素的增加,磁体密度增加;矫顽力先增高后降低,最大值在Gd取代1%Pr Nd时出现为14.77k Oe;而剩磁和最大磁能积都逐渐降低;磁体的剩磁温度系数和矫顽力温度系数的绝对值均随着Gd含量的增加而降低到-0.1080%/K和-0.6560%/K,不可逆磁通损失由27.1%降低到18.8%,居里温度对比原始磁体提高了12.64℃;5%Gd含量磁体内部出现富Gd相,起到一定润湿作用,对比富Nd相颜色偏灰,在主相中替代部分Pr Nd形成（Pr,Nd,Gd）₂Fe₁₄B主相结构,使得磁体致密度和热稳定性提高。（2）通过调整（Pr Nd）₃₁Ga_0.2Co₁Zr_0.2Al_xCu_yB_0.98Fe_65.82-x-y中Cu/Al元素的占比,分析了Cu/Al元素对未扩散磁体和磁控溅射扩散4/7/10/13μm Tb后磁体的磁性能及热稳定性;通过SEM和EDS表征方法,研究了Cu/Al的添加对其微观结构的影响:a)Al元素对于烧结后磁体的矫顽力在0.6%Al含量磁体中可达14.82 k Oe,在未进行扩散时就使得矫顽力提高了2.48 k Oe,扩散13μm后矫顽力达到22.19k Oe,对比未扩散未添加Al元素磁体提高了79.82%,而剩磁仅降低0.68 T,扩散后磁性能在Al元素的影响下得到较大提高;Cu元素对于烧结后磁体的矫顽力在0.4%Cu含量磁体中可达14.58 k Oe,在未进行扩散时就使得矫顽力提高了2.24 k Oe,扩散13μm后矫顽力达到22.51 k Oe,对比未扩散未添加Cu元素磁体提高了82.41%,而剩磁仅降低0.36 T,扩散后磁性能在Cu元素的影响下得到较大提高;b)添加Al磁体表面镀7μm Tb金属的矫顽力温度系数在0.6%Al含量磁体达到最大值-0.5601%/K,不可逆磁通损失（hirr）在加入Al后由28.89%降低到23.62%;而添加Cu磁体表面镀7μm Tb金属的矫顽力温度系数在0.3%Cu含量磁体达到最大值-0.5632%/K,180℃的不可逆磁通损失（hirr）在加入Cu后由28.89%降低到24.53%,磁体的温度稳定性在经过Cu/Al添加后都得到显著提升;c)通过对0.6%Al和0.4%Cu含量磁体表面镀7μm Tb金属扩散后的SEM表征,发现镀Tb金属以由晶界扩散到磁体内部,形成了Tb₂Fe₁₄B生成核壳结构,Al和Cu元素都增加了富钕相的占比,对于磁体镀Tb后的扩散效果显著增强。更多还原

【Abstract】 Sintered Nd Fe B,as the third generation of rare earth permanent magnet material,is widely used in new energy vehicles,intelligent manufacturing,medical and other high-tech industries due to its excellent magnetic properties.However,with the continuous increase of demand and output in different industries,the price of main raw materials has repeatedly set new highs,and the magnets have higher and higher requirements for coercivity and thermal stability.At present,in industry,dysprosium or terbium are often directly added during smelting to improve the coercivity of magnets and prepare Nd Fe B magnets with high comprehensive performance.However,the utilization rate of heavy rare earth is low,the production cost is high,and the remanence and magnetic energy product decrease greatly.On the one hand,through the design elements in it to join the lower prices,higher abundance of Gd elements to create excellent low price of sintered Nd-Fe-B magnet.On the other hand,by adjusting the structure of the matrix material of magnetron sputtering and improving the diffusion efficiency,a new idea is provided for reasonable and comprehensive utilization of rare earth elements.The main research contents are as follows:（1）Through adjusting Gd element content in the（Pr,Nd）_31-xGd_xFe_balAl_0.4Cu_0.2Ga_0.2Zr_0.2Co₁B_0.9 magnets,and analyses the influence of Gd contented magnet magnetic energy and the influence of temperature stability.The magnets were characterized by SEM and XRD methods to understand the microstructure by adding of Gd.The density of the magnet increases with the increase of Gd element.The maximum coercivity is 14.77 k Oe when Gd replaces 1%Pr Nd.Remanent magnetism and maximum magnetic energy product decrease gradually.With the increase of Gd content,the value of remanence temperature coefficient and coercivity temperature coefficient of the magnet decreased to-0.1080%/K and-0.6560%/K,the irreversible flux loss decreased from 27.1%to 18.8%,and the Curie temperature increased by12.64℃compared with the original magnet.The Gd-rich phase appears in the magnet with 5%Gd content,which plays a wetting role.Compared with the Nd-rich phase,the Gd-rich phase is grayer,and it replaces part of Pr Nd in the main phase to form（Pr,Nd,Gd）₂Fe₁₄B main phase structure,which improves the density and thermal stability of the magnet.（2）Through adjusting（Pr,Nd）₃₁Ga_0.2Co₁Zr_0.2Al_xCu_yB_0.98Fe_65.82-x-y of Cu/Al element in proportion.Analyses the magnetic and thermal stability of Cu/Al element not magnet and magnetron sputtering diffusion abilities by 4/7/10/13μm Tb after magnets.The effect of Cu/Al addition on its microstructure was studied by SEM and EDS characterization methods.A)The coercivity of Al element on sintered magnets is 14.82 k Oe in the magnet with 0.6%Al content.The coercivity increases by 2.48 k Oe without diffusion,and reaches 22.19 k Oe after diffusion of 13μm,79.82%higher than that of the magnet without diffusion and without adding Al element.The remanence decreases only by0.68 T,and the magnetic properties are greatly improved under the influence of Al element.The coercivity of Cu element on sintered magnets is up to 14.58 k Oe in the magnet with 0.4%Cu content.The coercivity increases by 2.24 k Oe without diffusion,and reaches 22.51 k Oe after diffusion of 13μm.Compared with the magnet without diffusion and without Cu element,the coercivity increases by 82.41%,while the remanence decreases by 0.36 T only.After diffusion,the magnetic properties are greatly improved under the influence of Cu element.B)The coercivity temperature coefficient of 7μm Tb metal coated on the surface of Al magnet reaches the maximum value-0.5601%/K at 0.6%Al content,and the irreversible flux loss（HIRR）decreases from 28.89%to 23.62%after Adding Al.The maximum coercivity temperature coefficient of Cu magnet coated with 7μm Tb metal reaches 0.5632%/K at 0.3%Cu content,and the irreversible flux loss（HIRR）at 180℃decreases from 28.89%to 24.53%after Cu/Al addition.The temperature stability of the magnet is significantly improved after Cu/Al addition.C)SEM characterization of the diffusion of 7μm Tb metal on the surface of 0.6%Al and 0.4%Cu magnets showed that the Tb-coated metal diffused from the grain boundary to the inner part of the magnets,forming the core shell structure of Tb₂Fe₁₄B.Al and Cu elements increased the proportion of neodymium-rich phase,and the diffusion effect of Tb-coated magnets was significantly enhanced.更多还原