Ni50Mn29Ga21Tbx磁性形状记忆合金的晶体结构研究

研究了Ni50Mn29Ga21Tbx系列磁性记忆合金不同状态下的晶体结构。列出了近年来发现的几种Ni-Mn-Ga合金的马氏体的详细资料。结果表明,在不改变Ni50Mn29Ga21合金组分的条件下,Tb的加入并没有改变合金的马氏体晶体结构。经过比较和计算,发现Ni50Mn29Ga21Tbx合金系列的晶体结构属于非调制型马氏体。     

Tb对Fe_(83)Ga_(17)合金磁致伸缩性能影响

主要研究了Tb对Fe-Ga合金的磁致伸缩性能影响。添加Tb后,Fe-Ga合金具有100晶向取向的晶粒数目有所增加,使磁致伸缩性能有了明显的提高。研究了Tb在Fe-Ga合金中的存在位置,Tb原子在合金的晶界处富集。     

Effects of Sm on Phase Transformation in Ni-Mn-Ga Alloys

The effects of small amount additions of Sm on the martensitic transition and magnetic phase transition of polycrystalline Ni-Mn-Ga alloys were investigated. The experimental results show that the Sm doped alloys also undergo a thermal-elastic martensitic transformation and reverse transformation during cooling and heating process and the addition of Sm decreases the martensitic transformation temperature and Curie temperature in different degree respectively. Ni-Mn-Ga alloys of adding Sm still possess Heusler structure, but their crystal lattice parameters are modified slightly. The addition of a proper amount of Sm does not basically decrease Tc of the alloy when avoiding the appearance of second phase. In addition, the doped alloys have favorable toughness because of grain refinement of Sm.     

真空磁场热处理对Tb0.3Dy0.7Fe1.95合金磁致伸缩性能的影响

研究了磁场热处理对Tb0.3Dy0.7Fe1.95多晶合金磁致伸缩性能的影响.将定向凝固得到的多晶合金,在真空条件下,加热到居里点附近不同温度,在加磁场下保温一定时间后冷却到室温,测量其磁致伸缩系数,并且进行X衍射分析.实验结果表明,在稍低于居里点的温度,沿垂直于棒的轴线加磁场保温一定时间后冷却,合金的磁致伸缩系数明显提高,沿样品棒轴线的晶体取向有一定程度的改变.     

Ni52 Mn23Ga24.5 Sm0.5合金的马氏体相变和磁致伸缩性能

研究了多晶Ni52 Mn23 Ga24．合金添加微量的稀土元素Sm后，对合金的马氏体相变和磁致伸缩性能的影响。结果发现，微量稀土元素Sm的掺入，降低了合金的马氏体相变温度和居里温度，但并未改变合金的晶体结构，同时由于晶粒细化作用，使合金室温时的磁致应变性能下降。     

成分及工艺对SmFe2系磁致伸缩性能的影响

研究了SmFe2合金中不同Sm、Fe比及添加Dy的磁致伸缩性能和力学性能,并且探讨了制备工艺和热处理对合金磁伸性能的影响.结果表明,Sm∶Fe为1∶1.87时,磁致伸缩性能最佳,用部分镝替代钐,可以提高材料的强度,热处理可以明显改善材料的磁致伸缩性能.     

Phase Transformation Behaviors and Effects of Terbium in Polycrystalline Ni-Mn-Ga Magnetic Shape Memory Alloys

The phase transformation behaviors of two kinds of magnetic shape memory alloys NisoMn25 x Ga25-x and Ni50 Mn29Ga21-x Tbx were studied. When the composition of Ni in these alloys was constant, increasing Mn and reducing Ga contents make martensitic transformation temperatures rise obviously. Simultaneously, thermal hysteresis of phase transformation reduce but Curie temperature una|ters. When terbium was added, phase transformation temperature went up further and Curie temperature kept constant. The alloys still show strong ferromagnetism and properties of thermoelastic martensite phase transformation.     

含铽多晶Ni-Mn-Ga磁性记忆合金的大磁感生应变

研究了含稀土Tb的多晶Ni50Mn29Ga21磁性形状记忆合金的磁感生应变效应。在一定的应力状态下，可获得-1．1％的大磁感生应变。稀土在明显地细化晶粒和提高材料力学性能的同时，不影响马氏体孪晶界面的运动，反而使应力作用下的磁感生应变效应进一步提高，使材料更具有实用性。     

Tb对多晶Ni52.5Mn23.5Ga24r合金马氏体相变和磁感生应变的影响

研究了添加不同量的Tb对多晶Ni52.5Mn23.5Ga24的马氏体相变和磁性能的影响,发现合金的马氏体相变温度显著提高,而在不加外应力的作用下合金的磁感生应变值却有所下降.     

稀土多晶Ni-Mn-Ga合金磁性能的研究

研究了多晶Ni50Mn29Ga21-xTbx合金系列的居里温度和饱和磁化强度.结果表明,适当地添加稀土Tb在明显提高材料力学性能的同时,保持了材料的原有居里温度和饱和磁化强度基本不变.微区成份能谱分析表明,稀土Tb在材料中主要存在于晶界.晶界上的Tb对材料的磁性能没有贡献,同时对晶粒内部Mn原子局域磁矩及其交换作用也没有明显的影响.