Fe及Fe83Ga17和Fe83Ga17Pr0.3合金的微结构与磁致伸缩性能

本研究对比研究了Fe、Fe_(83)Ga_(17)及Fe_(83)Ga_(17)Pr_(0.3)磁致伸缩材料的微结构与磁致伸缩性能。采用真空非自耗电弧炉在氩气保护下熔炼制备了合金样品。采用X射线衍射仪(XRD)和光学显微镜(OM)分析观察了合金样品的晶体结构和显微组织。采用扫描电镜配合能谱仪(SEM/EDS)测定了稀土Pr元素在Fe_(83)Ga_(17)Pr_(0.3)合金中的分布。通过电阻应变法测量了合金的磁致伸缩性能。结果表明:Fe和Fe_(83)Ga_(17)合金均由单一的bcc结构A2相组成,而Fe_(83)Ga_(17)Pr_(0.3)合金由A2主相和少量的富稀土Pr相组成。稀土Pr掺杂使合金中的A2相沿〈100〉晶向择优取向。Fe及Fe_(83)Ga_(17)和Fe_(83)Ga_(17)Pr_(0.3)合金的微观组织分别呈现细长的条状晶、晶粒粗大的等轴晶和晶粒细小的柱状晶。Fe的磁致伸缩系数为负值,而Fe_(83)Ga_(17)和Fe_(83)Ga_(17)Pr_(0.3)合金的磁致伸缩系数均为正值,三种材料的磁致伸缩系数绝对值的排序为FeFe_(83)Ga_(17)Fe_(83)Ga_(17)Pr_(0.3)。

Microstructure and Magnetostriction of Fe, Fe83Ga17 and Fe83Ga17Pr0.3 Alloys:a Comparative Study

The present work aimed to comparatively analyze microstructure and magnetostriction of Fe, and Fe₈₃Ga₁₇ and Fe₈₃-Ga₁₇Pr0.3 magnetostrictive alloys. We successfully prepared the alloys by employing a non-consumable vacuum arc melting furnace and applying a protective argon atmosphere, and observed crystal structures and surface morphologies of the alloys via X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS), respectively. The magnetostriction coefficients of the alloys were measured by means of resistance strain method. The results indicated that Fe and Fe₈₃Ga₁₇ alloy consist of a single phase of A2 with bcc structure, while the Fe₈₃Ga₁₇Pr0.3 alloy is composed of A2 phase and a small amount of Pr-rich phase. The Pr doping into Fe₈₃Ga₁₇ alloy facilitates the preferred growth in (100) orientation of A2 phase in the alloy. The microstructures of the Fe, Fe₈₃Ga₁₇ and Fe₈₃Ga₁₇Pr0.3 alloys present anisometric morphology with strip-like grains, the equiaxial morphology with coarse grains and a columnar structure with fine grains, respectively. The magnetostriction coefficient of Fe is negative, whereas the magnetostriction coefficients of Fe₈₃Ga₁₇ and Fe₈₃Ga₁₇Pr0.3 alloys are positive. The magnetostrictions of three alloys can be sequenced as Fe₈₃Ga₁₇Pr0.3>Fe₈₃Ga₁₇>Fe.