【作者】 李磊；

【导师】 刘家琴； 吴玉程；

【作者基本信息】 合肥工业大学 ， 材料工程（专业学位）， 2022， 硕士

【摘要】 作为第三代稀土永磁体的烧结Nd Fe B有着“磁王”的美誉,凭借其优异的磁性能以及超高的性价比而被广泛应用。尤其新能源产业的发展极大地增加了对Nd Fe B磁体的需求量。目前,烧结Nd Fe B具有较高的剩磁和磁能积,已接近其理论最大值,然而磁体矫顽力较低,与理论值之间仍存在较大差距,且磁体本身较差的温度稳定性严重限制了其使用范围。为了解决以上问题,一般通过添加重稀土元素的方式来提高磁体矫顽力。然而,重稀土资源储量低、成本高昂,过度使用不利于稀土资源的可持续发展。因此,在不使用重稀土元素的基础上制备性能优异的烧结Nd Fe B磁体越来越成为研究的热点方向。本文通过晶间掺杂少量（Pr Nd）H_x、纳米Al和Cu_{6 5}Ga₃₅制备了综合性能优异的烧结Nd Fe B磁体,为稀土元素的合理利用提供了一种新的思路,全文主要研究结果如下:（1）在含Al、Cu、Ga元素的Nd Fe B基础磁粉中掺杂（Pr Nd）H_x,研究了（Pr Nd）H_x掺杂对磁体的磁性能、温度稳定性、微观结构、耐腐蚀性能以及力学性能的影响,结果表明:（Pr Nd）H_x掺杂会造成磁体剩磁以及最大磁能积的降低,但大幅提升了磁体的矫顽力,使磁体具有更好的温度稳定性,并且不会改变主相成分,对磁体的居里温度不产生影响,微观结构的优化使得磁体的力学性得到了一定幅度的提高,但也导致其耐腐蚀性变差。（2）在不含Al、Cu、Ga元素的Nd Fe B基础磁粉中掺杂纳米Al或Cu₆₅Ga₃₅,研究了单相掺杂对磁体的磁性能和温度稳定性的影响。结果表明:掺杂纳米Al或Cu₆₅Ga₃₅均会造成剩磁以及最大磁能积的降低,但会提升磁体的矫顽力,并提高磁体的温度稳定性,其中掺杂Cu₆₅Ga₃₅更具优势,在矫顽力相近的情况下,掺杂Cu₆₅Ga₃₅的磁体具有更高的剩磁及最大磁能积。（3）在不含Al、Cu、Ga元素的Nd Fe B基础磁粉中进行纳米Al与Cu₆₅Ga₃₅共掺杂,研究了共掺杂对磁体磁性能、温度稳定性、微观结构、耐腐蚀性能以及力学性能的影响,结果表明:当0.2 wt%纳米Al与0.1wt%Cu₆₅Ga₃₅共掺杂,可使磁体矫顽力由12.38 k Oe提升至15.08 k Oe,而剩磁及最大磁能积仅小幅降低。磁体保持良好的温度稳定性以及较好的力学性能和耐腐蚀性能,磁体的居里温度受影响较小。但过高的Cu₆₅Ga₃₅掺杂量会大幅降低磁体密度以及增多孔隙,导致磁体的力学性能以及耐腐蚀性能变差。（4）相较于在含Al、Cu、Ga元素的基础磁粉上掺杂（Pr Nd）H_x,采用不含Al、Cu、Ga元素的基础磁粉进行纳米Al及Cu₆₅Ga₃₅共掺杂更具有优势,主要体现在:仅需0.2 wt%纳米Al以及0.1 wt%Cu₆₅Ga₃₅便可以达到掺杂3wt%（Pr Nd）H_x的效果,并且二者在磁性能以及稳定性上的差异较小,有效降低了稀土资源的使用。更多还原

【Abstract】 As the third generation of rare earth permanent magnets,sintered Nd Fe B has the reputation of“King of Magnets”.It is widely used due to the excellent magnetic properties and cost effective.Especially,the development of new energy industry has greatly increased the demand for Nd Fe B magnets.In current,sintered Nd Fe B has high remanence and magnetic energy product,which is close to the theoretical value.However,the low coercivity of the magnet,which is far lower than the theoretical value and the poor temperature stability of the magnets severely limit the application.I n order to solve these problems,the coercivity of magnets is generally improved by adding heavy rare earth elements.However,the scarcity and high cost make the excessive use unfavorable to the sustainable development of rare earth resources.Therefore,preparing the sintered Nd Fe B magnets of excellent performance without the addition of heavy rare earth elements has received much attention.Herein,sintered Nd Fe B magnets with comprehensive properties were prepared by intergranular doping a small amount of（Pr Nd）H _x,nano Al and Cu₆₅Ga₃₅,providing a new insight for rational utilization of rare earth elements.Main research results in this work can be summarized as following:（1）The effects of doped（Pr Nd）H_x on the magnetic properties,temperature stability,microstructure,corrosion resistance and mechanical properties of the magnets were studied by doping（Pr Nd）H_x into Nd Fe B-based magnetic powder containing Al,Cu and Ga elements.It shows that the dope of magnets with（Pr Nd）H_x results in the reduced remanence and the maximum magnetic energy product and greatly improved coercivity of the magnet,making the better temperature stability.The main phase and the Curie temperature of the magnet do not change.The optimization of the microstructure improves the mechanical properties of the magnet to a certain extent,while leads to the poor corrosion resistance to deteriorate.（2）The effect of single-phase doping on the magnetic properties and temperature stability of the magnet was studied by doping nano-Al and Cu₆₅Ga₃₅ into Nd Fe B-based magnetic powder without Al,Cu and Ga elements,respectively.It shows that the doped nano-Al or Cu₆₅Ga₃₅ induced the reduced the remanence and the maximum magnetic energy product,the improved coercivity and temperature stability of the magnet.The doped Cu ₆₅Ga₃₅ is superior in remanence and maximum energy product in the case of similar coercivity.（3）The effect of the co-doped magnets on the magnetic properties,temperature stability,microstructure,corrosion resistance and mechanical properties were studied by doping nano-Al and Cu₆₅Ga₃₅ into Nd Fe B-based magnetic powder without Al,Cu and Ga elements.It shows that:only 0.2wt%co-doped nano-Al and 0.1wt%Cu₆₅Ga₃₅ increased the coercivity from 13.32k Oe to 15.08 k Oe,while the remanence and maximum magnetic energy product decreased slightly.The magnet remains good temperature stability,mechanical properties and corrosion resistance,and the Curie temperature of the magnet is less affected.However,high doping amount of Cu₆₅Ga₃₅ greatly reduced density of the magnet and increases the number of holes,resulting in the poor mechanical properties and corrosion resistance of the magnet.（4）Compared with doped（Pr Nd）H_x of the basic magnetic powder containing Al,Cu and Ga elements,the co-doped nano-Al and Cu₆₅Ga₃₅ of the basic magnetic powder without Al,Cu and Ga elements is more advantageous,mainly reflected in:only 0.2wt%nano-Al and 0.1wt%Cu₆₅Ga₃₅ can achieve the similar effect of doping with 3wt%（Pr Nd）H_x.and the little difference in magnetic properties and stability,effectively reducing the use of rare earth resources.更多还原