微量Ce元素掺杂对Fe81Al19合金组织、取向与磁致伸缩性能的影响

Effect of Trace Doping Ce Element on Microstructure, Texture and Magnetostrictive Behavior of Polycrystalline Fe81Al19 Alloys

摘要:

Fe-Al合金兼具优异机械性能、低成本和中等磁致伸缩性能，是具有巨大应用潜力的新型磁致伸缩材料。本研究利用电弧熔炼制备(Fe₈₁Al₁₉)_100-xCe_x（x=0、0.05、0.1、0.2、0.3、0.4，at%）合金，分析微量稀土元素Ce对Fe₈₁Al₁₉合金的组织、织构和磁致伸缩性能的影响规律。结果表明：在Fe₈₁Al₁₉合金中添加微量Ce使等轴晶转变为柱状晶，并显著提升了有利的η织构体积分数。但柱状晶特征随着Ce含量提高逐渐减弱，导致了η织构的减弱和γ与α织构体积分数的提高。随着Ce元素含量的增加，晶界和晶粒内部区域形成大量富Ce的第二相。其中晶界处主要为富Ce-Al第二相，而在晶内为由Ce-Al包裹富Fe-Ce相的复合第二相。微量Ce元素掺杂显著提高了Fe₈₁Al₁₉合金的磁致伸缩性能，特别是当Ce含量为0.05%时，磁致伸缩系数达到峰值153 ppm，增幅达89%。磁致伸缩系数的显著提升归因于微量Ce元素添加形成更多包含η织构柱状晶以及微量Ce元素固溶导致更多纳米异质相的形成。

Abstract:

Fe-Al alloys exhibit excellent mechanical properties, low cost, and moderate magnetostriction, making it a promising magnetostrictive material. The polycrystalline (Fe₈₁Al₁₉)_100-xCe_x (x=0, 0.05, 0.10, 0.20, 0.30, 0.40, at%) alloys were prepared by arc melting. The effect of trace doping rare earth elements Ce on the microstructure, texture, and magnetostrictive behavior of Fe₈₁Al₁₉ alloys was investigated. Results show that the trace doping of the Ce element transforms the equiaxed crystals into columnar crystals, thus significantly improving the volume fraction of favorable η texture. The columnar crystal characteristics gradually weaken with the increase in Ce content, leading to weakening of η texture and an increase in the volume fraction of α and γ texture. With the increase in Ce content, a large amount of Ce-rich phases form at grain boundaries and within the grains. Among them, the phases at grain boundaries are mainly composed of Ce-Al-rich phases, while the phases within the grains is a composite secondary phase of Ce-Al wrapped around the Fe-Ce-rich phase. The magnetostriction of Fe₈₁Al₁₉ alloy is significantly enhanced by trace doping of Ce element. The peak magnetostriction of 153 ppm is obtained at the Ce element of 0.05at%, with an enhancement of 89% compared to the magnetostriction of a binary alloy. This improvement in magnetostriction is attributed to more columnar crystals containing η textures and the formation of more nanoheterogeneous phases owing to solid solution of trace Ce element .