The improvement of magnetic property by grain refinement using magnetic field annealing crystalline (Nd0.8Pr0.2)2.2Fe12Co2B ribbons
The improvement of magnetic property by grain refinement using magnetic field annealing crystalline (Nd0.8Pr0.2)2.2Fe12Co2B ribbons
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DOI：
10.1016/j.jmmm.2020.167434
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发表时间：
2020-10
影响因子：
2.7
通讯作者：
X. Tan;Yunfeng Tan;Yajie Tang;Shubo Sun;Shiyan Zhang;Hui Xu
中科院分区：
文献类型：
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作者：
X. Tan;Yunfeng Tan;Yajie Tang;Shubo Sun;Shiyan Zhang;Hui Xu
采用快淬法在15 m/s的速度下制备了（Nd 0.8Pr 0.2）2.2Fe 12 Co 2B薄带。研究了在573-723 K温度范围内，1 T磁场退火处理15 min对（Nd0.8Pr0.2）2.2Fe12Co2B薄带磁性能的影响，包括矫顽力、剩磁和最大磁能积（（BH）max）。在所研究的样品中，在673 K，1 T，15 min下获得了最大的（BH）max值。XRD结果表明，在673 K下，快淬薄带和磁退火样品均为Nd 2Fe 14 B（2：14：1）单相。（Nd0.8Pr0.2）2.2Fe12Co2B快淬薄带的晶粒尺寸为25 ± 3 nm，组织得到细化。1 T的磁场退火处理可使晶粒尺寸进一步减小到20 ± 1 nm。从晶粒长宽比和应力两个方面探讨了晶粒细化的机理。用Lorentz磁显微镜观察到在熔纺薄带和在673 K和1 T退火的样品中存在相互作用畴结构，表明2：14：1晶粒之间存在交换耦合。673 K磁退火样品的晶粒细化增强了交换耦合作用，导致剩磁和（BH）max分别提高了4%和6%。快淬（Nd_（0.8）Pr_（0.2））_（2.2）Fe_（12）Co_2 B）薄带的（BH）_（max）（141 kJ/m ~ 3）和1 T磁场退火薄带（150 kJ/m ~ 3）的（BH）_（max）均比某些含Dy的Nd-Fe-B永磁合金的（BH）_（max）大，提高幅度为7%~ 74%。
The (Nd0.8Pr0.2)2.2Fe12Co2B ribbons were prepared by melt-spinning at a wheel speed of 15 m/s. The effect of magnetic field annealing treatment with 1 T in the temperature range of 573–723 K for 15 min on the magnetic properties including parameters of the coercivity, the remanence, and the maximum energy product ((BH)max) of (Nd0.8Pr0.2)2.2Fe12Co2B ribbons was investigated. The largest value of (BH)maxamong sample studied is obtained at 673 K for 15 min with 1 T. XRD result shows that samples are crystalline state and single Nd2Fe14B (2:14:1) phase is observed in both melt-spun ribbon and magnetic annealing sample at 673 K. The refined microstructure with an average grain size of 25 ± 3 nm is obtained in crystalline (Nd0.8Pr0.2)2.2Fe12Co2B melt-spun ribbons. The magnetic field annealing treatment with 1 T can further reduce the average grain size to 20 ± 1 nm. The mechanism of grain refinement is discussed from two aspects including the length-to-width ratio of a grain and the stress. The interaction domain structure is observed in both melt-spun ribbon and the sample annealed at 673 K with 1 T by Lorentz magnetic microscopy suggesting the presence of the exchange coupling between 2:14:1 grains. The grain-refined microstructure of magnetic annealing sample at 673 K strengthens the exchange coupling interaction leading to an enhancement of the remanence and the (BH)max, with a rise of 4% and 6%, respectively. The values of (BH)maxof melt-spun (Nd0.8Pr0.2)2.2Fe12Co2B ribbon (141 kJ/m3) and annealed ribbon with 1 T magnetic field (150 kJ/m3) are both larger than that of some Dy-containing Nd-Fe-B permanent alloys with an improving range of 7%-74%.