【作者】 吴叶仁；

【导师】 严密；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2010， 硕士

【摘要】 烧结Nd-Fe-B磁体自诞生以来,因其优异的性价比而迅速产业化,是现今最具竞争力的永磁材料,但抗蚀性差和矫顽力低成为限制其进一步发展和应用的关键问题。磁体抗蚀性和矫顽力都对晶界相非常敏感,因此通过晶界相优化来提高磁体抗蚀性和矫顽力是非常有效的方法。本文分别采用单合金和双合金法制备烧结Nd-Fe-B磁体。系统研究了晶界添加Cu₆₀Zn₄₀合金粉、Mg₇₀Zn₃₀合金粉对磁体显微组织、抗蚀性以及磁性能的影响,并进行理论分析。同时还研究采用（Pr,Nd）_32.5Fe₆₂Cu_5.5辅合金优化晶界相对烧结Nd-Fe-B磁体显微组织、抗蚀性以及磁性能的影响,掌握了高抗蚀性磁体晶界相成分设计原理。主要研究结果如下:晶界添加Cu₆₀Zn₄₀合金粉、Mg₇₀Zn₃₀合金粉,有效提高了烧结Nd-Fe-B磁体晶界相电位,降低了相对钕含量,优化了显微组织,促使富钕相更均匀分布,提高了磁体密度,从而提高了磁体抗腐蚀性能。Cu₆₀Zn₄₀合金粉的添加使磁体在3.5 wt%NaCl溶液中抗腐蚀性能提高约一个数量级。此外,适量添加Cu₆₀Zn₄₀合金粉、Mg₇₀Zn₃₀合金粉,富钕相更均匀分布和主相晶粒的细化,使得矫顽力得到有效提高。采用（Pr,Nd）_32.5Fe₆₂Cu_5.5作为辅合金优化品界相,有效提高了磁体抗腐蚀性能和矫顽力。（Pr,Nd）_32.5Fe₆₂Cu_5.5添加量为12wt%磁体和稀土含量相当单合金法制备的RE_30.2B_0.96Fe_bal磁体在3.5wt%NaCl溶液中腐蚀电流密度分别是3.484μA/cm²、9.870μA/cm²,表明添加（Pr,Nd）_32.5Fe₆₂Cu_5.5磁体抗腐蚀性能得到明显提高。与未添加磁体相比,（Pr,Nd）_32.5Fe₆₂Cu_5.5添加量为12wt%磁体矫顽力增大约69%。更多还原

【Abstract】 Nd-Fe-B sintered magnets have been widely used in various applications due to their outstanding magnetic properties,and become the best important permanent magnets.However, poor corrosion resistance and low coercivity limit their applications and development.Both corrosion resistance and coercivity are very sensitive to intergranular phase.Therefore, modifying intergranular phase are very effective methods to improve both corrosion resistance and coercivity of Nd-Fe-B sintered magnets.In this dissertation,Nd-Fe-B sintered magnets were prepared by single alloy sintering method and binary alloy sintering method,respectively.Microstructure,corrosion resistance and coercivity of Nd-Fe-B sintered magnets with intergranular addition of Cu₆₀Zn₄₀ and Mg₇₀Zn₃₀ powders were systematically investigated and analyzed,respectively.Meanwhile,the intergranular phase was modified by adding（Pr,Nd）_32.5Fe₆₂Cu_5.5 alloy,and microstructure, corrosion resistance and coercivity of Nd-Fe-B sintered magnets were systematically investigated.The design principle of Nd-Fe-B sintered magnets with high corrosion resistance was suggested.The main results are as follows:Both corrosion resistance and magnetic properties of Nd-Fe-B sintered magnets are effectively improved with intergranular addition of Cu₆₀Zn₄₀ and Mg₇₀Zn₃₀ powders, respectively.Enhancement of the electrochemical potential of the intergranular phase,decrease of the total contents of Nd.uniform distribution of the Nd-rich phase and increase of magnet density are responsible for the corrosion resistance improvement.Especially.the corrosion resistance of magnets with intergranular addition of Cu₆₀Zn₄₀ powders is improved approximately one order of magnitude in 3.5 wt%NaCl solution.Moreover,the uniform distribution of Nd-rich phase and grains refined resulting in the enhancement of coercivity,and the increase of magnet density leading to the improvement of remanence and maximum energy product.Modifying intergranular phase by adding（Pr,Nd）_32.5Fe₆₂Cu_5.5 alloy can effectively improve corrosion resistance and coercivity of Nd-Fe-B sintered magnets.Corrosion current density of magnet with 12 wt%（Pr,Nd）_32.5Fe₆₂Cu_5.5 alloy and RE_30.2B_0.96Fe_bal magnets prepared by single alloy sintering method are 3.484μA/cm² and 9.870μA/cm² in 3.5 wt%NaCl solution, respectively,exhibiting that the corrosion resistance of magnets with the addition of （Pr,Nd）_32.5Fe₆₂Cu_5.5 alloy is effectively improved.Meanwhile,the enhancement of coercivity is about 69%in the case of 12 wt%（Pr,Nd）_32.5Fe₆₂Cu_5.5 alloy addition compared with that for additive-free magnet.更多还原