Tuneable structure and magnetic properties in Fe3−V Ge alloys
Tuneable structure and magnetic properties in Fe3−V Ge alloys
复制标题
DOI：
10.1016/j.jallcom.2020.154403
复制
发表时间：
2020-07
影响因子：
6.2
通讯作者：
R. Mahat;Shambhu Kc;D. Wines;F. Ersan;Shishir K. Regmi;U. Karki;R. White;C. Ataca;P. Padhan;A. Gupta;P. Leclair
中科院分区：
文献类型：
--
作者：
R. Mahat;Shambhu Kc;D. Wines;F. Ersan;Shishir K. Regmi;U. Karki;R. White;C. Ataca;P. Padhan;A. Gupta;P. Leclair
我们报道了V取代Fe原子对非化学计量fe3−x V x Ge金属间合金系列（0≤x≤1）的结构、磁性、输运、电子和力学性能的影响的详细实验和理论研究。当V含量x< 0.75时，合金为单相组织，而当V含量x≥0.75时，合金为多相组织。差示扫描量热法结果证实，钒取代引起无扩散马氏体相变，由类heusler L2 - 1结构转变为六方DO - 19结构。钒的取代还可以减小晶粒尺寸，通过抑制晶界迁移来抑制晶粒的生长。该系列合金在5 K时均为软铁磁体，饱和磁矩和居里温度随V浓度的增加而降低。低温饱和磁矩与L2 - 1相的预期Slater-Pauling值接近，而六边形样品的饱和磁矩值明显更高。第一性原理计算与实验结果一致，表明V取代在能量上有利于fe3ge中的一个Fe位。在5 ~ 400 K温度范围内的电阻率测量表明，随着V浓度的增加，高温下电阻率温度系数为负。同时观察到较高的机械硬度值，且随V含量的增加而升高。研究发现，钒取代在调节材料的力学性能、稳定L2 - 1结构和使马氏体相变温度从母体Fe - 3ge升高到更高的温度方面起着核心作用。
We report a detailed experimental and theoretical study of the effects of V substitution for Fe atom on the structural, magnetic, transport, electronic and mechanical properties of an off-stoichiometric Fe 3− x V x Ge intermetallic alloy series (0≤ x≤ 1). Single phase microstructures are observed for x< 0.75, whereas higher V content alloys x≥ 0.75 are multi-phased. Vanadium substitution is observed to induce a diffusionless martensitic phase transformation from a Heusler-like L2 1 structure to hexagonal DO 19 structure, as corroborated by Differential Scanning Calorimetry results. The vanadium substitution is also found to decreases the grain size, inhibiting the grain growth by pinning the grain boundary migration. All the alloys in the series are found to be soft ferromagnets at 5 K with saturation magnetic moment and Curie temperature decreasing as V concentration increases. The low temperature saturation magnetic moment is in close agreement with the expected Slater-Pauling values for the L2 1 phases, while the hexagonal samples have markedly higher values of saturation moments. First-principle calculations agree with the experimental findings and reveal that V substitution energetically favours one of the Fe sites in Fe 3 Ge. The electrical resistivity measured over the temperature range from 5 K to 400 K shows negative temperature coefficient of resistivity at high temperatures with increasing the V concentration. Relatively high mechanical hardness values are also observed, with the values increasing with increasing V content. Vanadium substitution is found to play a central role in tuning the mechanical properties, stabilising the L2 1 structure, and shifting the martensitic transformation temperature to higher values from that of parent Fe 3 Ge.