【摘要】 采用定向凝固技术制备多晶合金 ,使合金获得择优取向 ,并研究这种择优取向对磁感生应变的影响 .研究结果表明 ,多晶Ni Mn Ga RE(RE =Tb ,Sm)合金定向凝固生长以后 ,在一定晶体学方向上发生择优取向 ,可以显著提高合金的磁感生应变值 .在同等大小的磁场下 ,定向凝固试样的磁感生应变值比铸态试样的应变值高出很多 ,特别是在高磁场下 (>0 5T) ,定向凝固试样的磁感生应变值约为相同成分的铸态试样的 2倍 .所以 ,定向凝固工艺是制备具有择优取向晶体并获得大磁感生应变的一种有效方法 .更多还原

【Abstract】 The polycrystalline Ni-Mn-Ga-RE(RETb,Sm) alloys with oriented crystal structures were prepared by the technique of directional solidification. Investigations were made on the effects of oriented crystal structures on the magnetic-field-induced strains of the alloys. The experimental results show that the oriented crystal structures increase remarkably the magnetic-field-induced strains of the magnetic shape memory alloys. As the magnetic field with the same magnitude was applied, the strain values of the directional solidification samples were higher than those of as-cast samples. Especially in a strong magnetic field (>0.5T), the strain values of the samples with oriented crystal structures are twice as large as those of the as-cast samples with the same composition. Therefore, the technique of directional solidification is an effective way to prepare the oriented Ni-Mn-Ga crystal and promote the magnetic-field-induced strain.更多还原