低镝烧结钕铁硼磁体组织调控及应用
发布时间：2018-11-12 14:13
【摘要】：本文采用粉末冶金工艺制备了两套低镝高矫顽力烧结钕铁硼磁体的工艺制度。开发出一套低镝低成本烧结钕铁硼磁体的制造工艺。采用本文的双主相降镝技术制备的双主相磁体,比常规磁体矫顽力大幅增高,基于简化的模型对双主相磁体矫顽力的增强机制给出了定性解释。采用本文的工艺制备磁体,实现了重稀土资源的高效利用。对烧结钕铁硼磁体冲击退磁进行了研究。全文主要结论如下：(1)成功研制出名义成分为Nd28.2DY2Fe68.8B的48SH,((BH) m=382kJ/m3, Hcj=1548 kA/m)低镝高矫顽力烧结钕铁硼磁体。合适厚度的富Nd相,可以使重稀土的得到优质化利用。(2)分析了磁体中晶粒异常长大的原因,并在此基础上摸索出一套制备低镝低成本烧结钕铁硼磁体的工艺制度。通过制粉控制使磁体大部分的氧元素存在于晶界相中,这种工艺减少了原料浪费并缩短了生产时间,大大降低了磁体的生产成本。通过晶界的氧含量调控,改善高矫顽力磁体的烧结工艺制度。(3)通过研究,获得了一种降镝技术。制备的磁体被命名为双主相磁体,它比常规的单合金法制备的磁体矫顽力大幅增高。首次制备并表征出双主相磁体中含有两种各向异性场不同的(Nd-Fe-B和Dy-Fe-B)晶粒结构。考虑了体积分数和晶粒尺寸对双主相磁体矫顽力的影响, 给出半经典公式：用形核场控制矫顽力机制对双主相磁体矫顽力的增强效应给出了定性解释。(4)制备了不同晶粒尺寸的双主相磁体,磁体综合磁性能最佳时,(BH)研究了磁体晶粒尺寸与晶界相的关联效应,随着磁体平均晶粒尺寸逐渐减小,主相晶粒尺寸分布集中,晶粒形貌变得规则。磁体角隅晶界处的富钕相尺寸较小,这就增加了条带状晶界相的数量,减少了角隅晶界相的比例,使磁体矫顽力提高。(5)开展了不同压力的冲击波对烧结钕铁硼的加载实验,冲击波在磁体内呈线性方式衰减。烧结钕铁硼磁体退磁的临界压力不高于4.99 GPa。当冲击波压力在6.26≤P≤7.21 GPa之间时,磁体表面出现明显的沿晶断裂。随着冲击压力的增加磁体取向度变差,磁体遭受冲击后主相晶粒的取向发生偏转。在900℃和520℃,先后回火2个小时后,磁体的矫顽力恢复,沿晶断裂的现象消失。冲击后磁体的晶界相晶体结构没有发生改变。磁体发生退磁的原因应该为：在磁体遭受冲击瞬间,主相晶粒在高温高压的作用下挤压富Nd晶界相,薄区富Nd相受到高温挤压向周围移动导致主相晶粒相互连通；在冲击后的磁体的晶界相中存在大量的微裂纹和孔洞,这些微裂纹和孔洞周围形成低各向异性区,成核场减弱；晶界相的滑移和断裂改变了主相和晶界相的取向关系。提高磁体最大磁能积的同时降低磁体的抗冲击性可增强功率源输出功率。
[Abstract]:Two sets of NdFeB magnets with low dysprosium and high coercivity were prepared by powder metallurgy. A set of low dysprosium and low cost sintered NdFeB magnets was developed. The coercivity of the dual principal phase magnets prepared by the double principal phase drop dysprosium technique is much higher than that of the conventional magnets. Based on the simplified model, the mechanism of the coercivity enhancement of the dual principal phase magnets is explained qualitatively. The magnets were prepared by the technology in this paper, and the high efficiency utilization of heavy rare earth resources was realized. The impact demagnetization of sintered NdFeB magnets was studied. The main conclusions of this paper are as follows: (1) 48SHS, (BH) mN382kJ / m3, Hcj=1548 kA/m with nominal composition of Nd28.2DY2Fe68.8B have been successfully fabricated. The magnets sintered with low dysprosium and high coercivity have been successfully sintered into NdFeB magnets with low dysprosium and high coercivity. The rich Nd phase of suitable thickness can make the heavy rare earth get the excellent quality and utilization. (2) the reason of the abnormal grain growth in the magnet is analyzed, and on the basis of this, a set of process system for preparing low dysprosium and low cost sintered NdFeB magnets is found out. By means of pulverizing control, most of the oxygen elements of the magnets are present in the grain boundary phase. This process reduces the waste of raw materials, shortens the production time and greatly reduces the production cost of the magnets. The sintering process of high coercivity magnets was improved by controlling the oxygen content in grain boundaries. (3) A dysprosium reduction technique was obtained through research. The prepared magnets are named as two-phase magnets and the coercivity of the magnets prepared by single alloy method is much higher than that of conventional single-alloy magnets. Two kinds of anisotropic (Nd-Fe-B and Dy-Fe-B) grain structures have been prepared and characterized for the first time. The effects of volume fraction and grain size on the coercivity of the two-phase magnet are considered. The semiclassical formula is given: the enhancement effect of the coercivity of dual main phase magnets is explained qualitatively by means of nucleation field control coercivity mechanism. (4) two main phase magnets with different grain sizes are prepared, when the comprehensive magnetic properties of the magnets are optimal, The correlation effect between grain size and grain boundary phase is studied by (BH). With the decrease of average grain size of magnet, the distribution of main phase grain size is concentrated, and the grain morphology becomes regular. The size of the neodymium rich phase at the corner of the magnet is smaller, which increases the number of striped grain boundary phases and reduces the proportion of the corner grain boundary phases. The coercivity of magnets is improved. (5) the loading experiments of sintered NdFeB with shock wave at different pressures are carried out, and the shock wave attenuates linearly in the magnetic body. The critical pressure of sintered NdFeB magnets for demagnetization is no more than 4.99 GPa. When the shock wave pressure is 6.26 鈮，
本文编号：2327348
[Abstract]:Two sets of NdFeB magnets with low dysprosium and high coercivity were prepared by powder metallurgy. A set of low dysprosium and low cost sintered NdFeB magnets was developed. The coercivity of the dual principal phase magnets prepared by the double principal phase drop dysprosium technique is much higher than that of the conventional magnets. Based on the simplified model, the mechanism of the coercivity enhancement of the dual principal phase magnets is explained qualitatively. The magnets were prepared by the technology in this paper, and the high efficiency utilization of heavy rare earth resources was realized. The impact demagnetization of sintered NdFeB magnets was studied. The main conclusions of this paper are as follows: (1) 48SHS, (BH) mN382kJ / m3, Hcj=1548 kA/m with nominal composition of Nd28.2DY2Fe68.8B have been successfully fabricated. The magnets sintered with low dysprosium and high coercivity have been successfully sintered into NdFeB magnets with low dysprosium and high coercivity. The rich Nd phase of suitable thickness can make the heavy rare earth get the excellent quality and utilization. (2) the reason of the abnormal grain growth in the magnet is analyzed, and on the basis of this, a set of process system for preparing low dysprosium and low cost sintered NdFeB magnets is found out. By means of pulverizing control, most of the oxygen elements of the magnets are present in the grain boundary phase. This process reduces the waste of raw materials, shortens the production time and greatly reduces the production cost of the magnets. The sintering process of high coercivity magnets was improved by controlling the oxygen content in grain boundaries. (3) A dysprosium reduction technique was obtained through research. The prepared magnets are named as two-phase magnets and the coercivity of the magnets prepared by single alloy method is much higher than that of conventional single-alloy magnets. Two kinds of anisotropic (Nd-Fe-B and Dy-Fe-B) grain structures have been prepared and characterized for the first time. The effects of volume fraction and grain size on the coercivity of the two-phase magnet are considered. The semiclassical formula is given: the enhancement effect of the coercivity of dual main phase magnets is explained qualitatively by means of nucleation field control coercivity mechanism. (4) two main phase magnets with different grain sizes are prepared, when the comprehensive magnetic properties of the magnets are optimal, The correlation effect between grain size and grain boundary phase is studied by (BH). With the decrease of average grain size of magnet, the distribution of main phase grain size is concentrated, and the grain morphology becomes regular. The size of the neodymium rich phase at the corner of the magnet is smaller, which increases the number of striped grain boundary phases and reduces the proportion of the corner grain boundary phases. The coercivity of magnets is improved. (5) the loading experiments of sintered NdFeB with shock wave at different pressures are carried out, and the shock wave attenuates linearly in the magnetic body. The critical pressure of sintered NdFeB magnets for demagnetization is no more than 4.99 GPa. When the shock wave pressure is 6.26 鈮，
本文编号：2327348
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