系统研究了 Ni55-x CuxFe18 Ga27熔炼和甩带样品的结构和相变。研究结果表明：对于熔炼 Ni55-x-CuxFe18Ga27(x=0,2.5,3.2,3.5,4,7,10,11,14,16),随着Cu含量的增加,马氏体相变温度由292 K逐渐降低至125 K。Cu替代Ni引起过渡金属近邻原子间相互交换作用的增强,导致居里温度除个别偏离外均随Cu含量增加而升高。这一特点表明,该类合金在高温处仍具有铁磁性。对于甩带 Ni55-xCuxFe18 Ga27(x=1,2,3,4),X射线衍射谱表明样品为纯的 L21结构且晶格常数逐渐增大,克服了熔炼样品伴有γ相的缺点。甩带样品晶格常数增大导致过渡金属中3d电子之间 d-d轨道交换相互作用减弱,引起马氏体相变温度降低。%The structure and phase transition of Ni55-x CuxFe18 Ga27 alloys prepared by arc-melting and melt-spinning techniques were systematically investigated in this paper.For arc-melting Ni55-xCuxFe18 Ga27 (x=0,2.5,3.2, 3.5,4,7,10,11,14,16)alloys,the martensitic transformation temperature reduced gradually from 292 K to 125 K with increasing Cu content.Substitution of Ni by Cu enhanced the exchange interaction among neighboring atoms in the transition metals,leading to increasing Curie temperature,except for some individual cases.This characteristic demonstrates that Ni55-x CuxFe18 Ga27 alloys retain their ferromagnetism at even high temperature.The structure of melt-spinning Ni55-xCuxFe18 Ga27 (x=1,2,3,4)alloys maintains pure L21-type with increasing lattice constant,which overcomes theγphase in arc-melting samples.The increase of lattice constant in ribbon reduces exchange interaction between 3d electrons in the transition metals,thus decreases the martensitic transformation temperature.
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