取向多晶Mn_(1.9)Co_(0.1)Sb的磁弹性相变和巨各向异性磁致应变效应

Magnetoelastic transition and giant anisotropic magnetostriction effect in textured Mn_(1.9)Co_(0.1)Sb polycrystal

Mn2Sb基合金磁弹性相变附近具有丰富可调的磁功能性质,再加上其低廉的成本,在很多领域都具有潜在应用,然而合金有关磁致应变的研究和报道仍然非常少.本文利用合金在电弧熔炼过程中,由于快速冷却而产生强烈温度梯度,从而导致晶体生长出现高度择优取向性,制备出取向性的Mn_(1.9)Co_(0.1)Sb多晶合金.X射线衍射和热磁测量都表明合金晶粒沿着特定晶体学方向生长.等温磁化曲线表明合金发生了明显的磁场驱动变磁性相变,且变磁性行为随测量温度的降低越发明显.利用标准的电阻式应变片方法直接测量了其磁致应变效应,获得了测量方向分别平行和垂直于织构方向高达0.246%和-0.11%的巨各向异性磁致应变值.该磁致应变效应主要起源于合金磁场诱导变磁性相变附近各向异性的晶格畸变.

Mn_(2)Sb-based alloys have extremely promising practical applications in many fields owing to their abundant and controllable magnetofuntional properties around the first-order magnetoelastic transition, as well as their low costs.However, only a few studies on the magnetostrain of these alloys have been reported. Herein, a highly textured Mn_(1.9)Co_(0.1)Sb polycrystal is fabricated by using the arc-melting technique, which produces a strong temperature gradient induced by rapid cooling during the arc-melting process, resulting in the highly selective orientation of crystal growth. Xray diffraction and thermomagnetic measurements show that the grains grow in certain crystallographic directions.Metamagnetic transition is revealed by the isothermal magnetization curve measurements, which is observed to be more obvious at lower temperatures. The standard resistive strain-gauge method is adopted to measure the magnetostriction effect. Giant anisotropic magnetostrain values of up to 0.246% and -0.11% are obtained parallel and vertical to the texture of the alloy, respectively. This magnetostriction effect mainly originates from the anisotropic lattice distortion across the first-order magnetoelastic phase transition.