Research on Development of Ferromagnetic Shape Memory Alloy

本研究旨在开发一种既具有铁磁性又具有形状记忆效应的新型铁磁形状记忆合金。首先，我们通过反复试验发现了Fe62-Cr13-Co10-Ni7-Si6-Mn2[wt%]合金。在这种复合体系中，通过热处理可以改善形状记忆效应，但同时铁磁性能也有所恶化。在类似的无钴体系中，我们优化了组成比。结果表明，Fe68-Cr13-Ni7-Si6-Mn6[wt%]合金具有良好的磁致伸缩性能(100%)，其饱和磁化强度ms为65.8[emu/g]。在这项研究中，我们明确了每个组分的作用，即每个元素对磁性能和形状记忆性能的影响。采用熔体旋压技术制备了新型铁磁形状记忆合金。阐明了制备含锰量在14%以上的带材的工艺条件，并研究了在Fe-Cr-Si-Mn系中添加稀土元素。加入近1%的稀土元素，未经热处理的样品的饱和磁化强度可达80[emu/g]以上，但热处理后的磁性能有所恶化。优化后发现，Fe58.1-Mn26-Cr10-Si5-Nd0.7-B0.2[wt%]合金具有完美的SME(100%)，饱和磁化强度大于60[emu/g](970℃加热30秒后快速冷却)；Fe57.9-Mn26-Cr10-Si4.9-Sm1-B0.2[wt%]合金具有完美的SME(100%)和高于87.9[emu/g]的饱和磁化强度(910℃加热40 s后快速冷却)。本研究开发的材料在磁性传感器和执行器领域具有广泛的应用前景。

This research has been carried out to develop a new ferromagnetic shape memory alloy, which has both ferromagnetic property and shape memory effect itself. Firstly we have discovered Fe62-Cr13-Co10-Ni7-Si6-Mn2[wt%] alloy in trial and error. In this composition, we were able to improve the shape memory effect(SME) by heat treatment, however the ferromagnetic property deteriorated in the same time. In the similar system without cobalt, we have optimized the composition ratio. As a result, Fe68-Cr13-Ni7-Si6-Mn6[wt%] alloy showed an excellent SME(100%) and its saturation magnetization Ms was equal to 65.8 [emu/g]. In this research, we have made clear the role of each component, that is, influence of each element on the magnetic properties and the shape memory properties. The new ferromagnetic shape memory alloys have been produced by means of the melt spinning technique. The condition how to produce the ribbon, which contains higher manganese composition over 14%, has also clarified.In addition, we have investigated to add rare earth elements for the Fe-Cr-Si-Mn system. The samples without heat-treatment, had higher saturation magnetization over 80[emu/g] by adding nearly one percent of a rare earth element, however the magnetic property deteriorated after the heat-treatment in similarly. After optimisation, we have found out that Fe58.1-Mn26-Cr10-Si5-Nd0.7-B0.2[wt%] alloy had the perfect SME (100%) and the high saturation magnetization over 60[emu/g](under rapid cooling after heating at 970℃ for 30 seconds) and Fe57.9-Mn26-Cr10-Si4.9-Sm1-B0.2[wt%] alloy had the perfect SME(100%) and the high saturation magnetization over 87.9[emu/g](under rapid cooling after heating at 910℃ for 40 seconds). The materials developed in this research have wide application in the field of the magnetic sensors and actuators.