Chiu Wan-Ting, Watanabe Yui, Tahara Masaki, Inamura Tomonari, Hosoda Hideki
Institute of Innovative Research (IIR), Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.
Micromachines (Basel). 2023 Aug 14;14(8):1604. doi: 10.3390/mi14081604.
Ferromagnetic shape memory alloys (FSMAs), which are potential candidates for future technologies (i.e., actuators in robots), have been paid much attention for their high work per volume and rapid response as external stimulation, such as a magnetic field, is imposed. Among all the FSMAs, the Ni-Mn-Ga-based alloys were considered promising materials due to their appropriate phase transformation temperatures and ferromagnetism. Nevertheless, their intrinsic embrittlement issue and sluggish twin motion due to the inhibition of grain boundaries restrict their practicability. This study took advantage of the single-crystal Ni-Mn-Ga cube/silicone rubber composite materials to solve the two aforementioned difficulties. The single-crystal Ni-Mn-Ga cube was prepared by using a high-temperature alloying procedure and a floating-zone (FZ) method, and the cubes were verified to be the near-{100} Ni-Mn-Ga alloy. Various room temperature (RT) curing silicone rubbers were utilized as matrix materials. Furthermore, polystyrene foam particles (PFP) were used to provide pores, allowing a porous silicone rubber matrix. It was found that the elastic modulus of the silicone rubber was successfully reduced by introducing the PFP. Additionally, the magnetic field-induced martensite variant reorientation (MVR) was greatly enhanced by introducing a porous structure into the silicone rubber. The single-crystal Ni-Mn-Ga cube/porous silicone rubber composite materials are considered to be promising materials for applications in actuators.
铁磁形状记忆合金（FSMAs）作为未来技术（如机器人中的致动器）的潜在候选材料，因其单位体积的高功以及在施加外部刺激（如磁场）时的快速响应而备受关注。在所有的铁磁形状记忆合金中，基于Ni-Mn-Ga的合金由于其合适的相变温度和铁磁性而被认为是有前途的材料。然而，它们固有的脆化问题以及由于晶界抑制导致的缓慢孪生运动限制了它们的实用性。本研究利用单晶Ni-Mn-Ga立方体/硅橡胶复合材料来解决上述两个难题。通过高温合金化工艺和悬浮区（FZ）法制备了单晶Ni-Mn-Ga立方体，并验证这些立方体为近{100} Ni-Mn-Ga合金。使用了各种室温（RT）固化的硅橡胶作为基体材料。此外，聚苯乙烯泡沫颗粒（PFP）被用于提供孔隙，从而形成多孔硅橡胶基体。结果发现，通过引入PFP成功降低了硅橡胶的弹性模量。此外，通过在硅橡胶中引入多孔结构，极大地增强了磁场诱导的马氏体变体再取向（MVR）。单晶Ni-Mn-Ga立方体/多孔硅橡胶复合材料被认为是用于致动器应用的有前途的材料。
