In this study, micromagnetism simulation by using timte dltterence method is cameo out on the Ncl21-el415/a-Fe nanocomposite magnet with soft phase imbedded in hard phase. The effects of soft magnetic phase size （S）...In this study, micromagnetism simulation by using timte dltterence method is cameo out on the Ncl21-el415/a-Fe nanocomposite magnet with soft phase imbedded in hard phase. The effects of soft magnetic phase size （S） on the magnetic properties and magnetic reversal modes are systematically analyzed. As S increases from 1 nm to 48 nm, the remanence （Jr） increases, while the coercivity （Hci） decreases, leading to the result that the magnetic energy prod- uct [（BH）max] first increases slowly, and then decreases rapidly, peaking at S = 24 nm with the （BH）max of 72.9 MGOe （1 MGOe = 7.95775 kJ.m-3）. Besides, with the increase of S, the coercivity mechanism of the nanocomposite magnet changes from nucleation to pinning. Furthermore, by observing the magnetic moment evolution in demagnetization pro- cess, the magnetic reversal of the soft phase in the nanocomposite magnet can be divided into three modes with the increase of S： coherent rotation （S 〈 3 nm）, quasi-coherent rotation （3 nm≤S 〈 36 nm）, and the vortex-like rotation （S ≥36 nm）.展开更多
回收利用是稀土资源高效利用的可持续方案.氢化破碎技术因其高效环保特性被广泛采用,但氢破过程中产生的混合相会显著降低回收效率,这对工艺的优化提出了新的挑战.本文采用基于第一性原理计算结合机器学习方法,通过德拜模型系统地探究...回收利用是稀土资源高效利用的可持续方案.氢化破碎技术因其高效环保特性被广泛采用,但氢破过程中产生的混合相会显著降低回收效率,这对工艺的优化提出了新的挑战.本文采用基于第一性原理计算结合机器学习方法,通过德拜模型系统地探究了氢化破碎过程中关键稀土氢化物(如NdH_(2),NdH_(3),Nd_(2)H_(5))的热力学行为.研究结果表明,在600 k Pa压强下,630 K左右的温度区间有望为氢化破碎工艺提供一个较为理想的操作条件.在此条件下,NdH_(2)能够实现自发氢化,且能够有效抑制非稳定相的形成,有助于提高稀土回收效率.本研究还揭示了过高温度对NdH_(2)热力学性质可能产生的不利影响,进一步强调了在特定温度区间操作的重要性.这些发现不仅为理解钕铁硼氢化过程的热力学机理提供了新的视角,而且为工业应用中氢化破碎工艺参数的优化提供了理论参考.展开更多
基金Project supported by the Key Program of the National Natural Science Foundation of China(Grant No.51331003)the International S&T Cooperation Program of China(Grant No.2015DFG52020)+1 种基金the General Program of Science and Technology Development Project of Beijing Municipal Education Commission,China(Grant No.KM201710005006)the State Key Laboratory of Advanced Metals and Materials,China(Grant No.2015-ZD02)
文摘In this study, micromagnetism simulation by using timte dltterence method is cameo out on the Ncl21-el415/a-Fe nanocomposite magnet with soft phase imbedded in hard phase. The effects of soft magnetic phase size （S） on the magnetic properties and magnetic reversal modes are systematically analyzed. As S increases from 1 nm to 48 nm, the remanence （Jr） increases, while the coercivity （Hci） decreases, leading to the result that the magnetic energy prod- uct [（BH）max] first increases slowly, and then decreases rapidly, peaking at S = 24 nm with the （BH）max of 72.9 MGOe （1 MGOe = 7.95775 kJ.m-3）. Besides, with the increase of S, the coercivity mechanism of the nanocomposite magnet changes from nucleation to pinning. Furthermore, by observing the magnetic moment evolution in demagnetization pro- cess, the magnetic reversal of the soft phase in the nanocomposite magnet can be divided into three modes with the increase of S： coherent rotation （S 〈 3 nm）, quasi-coherent rotation （3 nm≤S 〈 36 nm）, and the vortex-like rotation （S ≥36 nm）.
文摘回收利用是稀土资源高效利用的可持续方案.氢化破碎技术因其高效环保特性被广泛采用,但氢破过程中产生的混合相会显著降低回收效率,这对工艺的优化提出了新的挑战.本文采用基于第一性原理计算结合机器学习方法,通过德拜模型系统地探究了氢化破碎过程中关键稀土氢化物(如NdH_(2),NdH_(3),Nd_(2)H_(5))的热力学行为.研究结果表明,在600 k Pa压强下,630 K左右的温度区间有望为氢化破碎工艺提供一个较为理想的操作条件.在此条件下,NdH_(2)能够实现自发氢化,且能够有效抑制非稳定相的形成,有助于提高稀土回收效率.本研究还揭示了过高温度对NdH_(2)热力学性质可能产生的不利影响,进一步强调了在特定温度区间操作的重要性.这些发现不仅为理解钕铁硼氢化过程的热力学机理提供了新的视角,而且为工业应用中氢化破碎工艺参数的优化提供了理论参考.
