Mn_（50）Ni_（39）Sn_（11-x）Al_x合金的磁相变及磁卡效应

Ni-Mn基铁磁Heusler合金的巨大磁卡效应使其在磁制冷方面具有良好的应用前景.磁熵变是磁卡效应的重要量度,根据麦克斯韦关系,磁熵变不仅与马氏体相变前后磁矩的变化大小△Msf有关,而且与马氏体相变温度跨度（Martensitic Transition Temperature Range,MTTR）有关.本文中,我们制备了Mn50Ni39Sn11△xAlx（x=0,1,2）系列合金样品,发现随着Al含量的升高,虽然△Msf减小,但MTTR随Al含量增加的减少更快,使得（△Msf/MTTR）值增大,从而获得较大的磁熵变△SM.以上结果表明除增大△Msf外,降低MTTR值也是提高材料磁卡效应的有效方法.

Magnetic transition and magnetocaloric effect of Mn50Ni39Sn11-xAlx alloys

Ni-Mn based Heusler alloy has a great potential application in practice due to its giant magnetocaloric effect. According to the Maxwell relation, the value of magnetic entropy （ASM） change is not only determined by the magnetization difference of AMsf, but also by the range of martensitic transition temperature （MTTR）. In this work, a series of MnsoNi39Sn11-xAlx （x=0, 1, 2） ferromagnetic shape memory alloys were prepared to study the effect of A1 substitution on the magnetoentropy. The results indicate that although the magnetization of MnsoNi39SnH-xAlx decreases by the A1 introduction, the MTTR decreases greatly with increasing A1 concentration, even more sensitive and sharper than that of magnetization, and results in a large ASM for enhancing on AMsf/MTTR. The work proves that it is another effective method to obtain the large magnetic entropy by reducing the MTTR in addition to enlarging the AMsf.