Ni_(50)Mn_(27)Ga_(23)快淬薄带的马氏体相变和磁感生应变

Martensitic Transformation and Magnetic-Field-Induced Strains in Ni_(50)Mn_(27)Ga_(23) Melt-Spun Ribbons

采用快淬技术制备了非化学计量成分的Ni50Mn27Ga23多晶薄带,对快淬薄带的马氏体相变和磁感生应变进行了研究。结果表明,快淬薄带在冷却和加热过程中仍然发生热弹性马氏体相变及逆相变,具有典型的热弹性形状记忆效应,并且比铸态合金具有更大的应变,但是马氏体相变温度下降。快淬工艺在合金内部引入特定的内应力,使薄带形成织构,是合金获得更大相变应变和磁感生应变的原因。热处理后,内应力大大降低,导致磁感生应变降低。

The non-stoichiometric Ni50Mn27Ga23 polycrystalline ribbons were prepared by melt-spinning technique. The martensitic transformation and the magnetic-field-induced strain of melt-spun ribbons were investigated. The experimental results show that the ribbons still undergo thermal-elastic martensitic transformation and reverse transformation in cooling and heating process. The melt-spun ribbons exhibit typical thermo-elastic shape memory effect and larger strain than as-cast specimens, but martensitic transformation temperature decreases. The reason which makes melt-spun ribbons have larger martensitic-transformation-strain and magnetic-fieldinduced strain is that the particular internal stress induced by melt-spinning makes a texture form in the melt-spun ribbons. That the internal stress is released strongly by heat treatment results in a decrease of the magnetic-field-induced strain.