Ni-Mn-Ga铁磁记忆合金质子辐照效应及其机理研究

Proton irradiation plays an important role in the lifetime and the reliability of the spacecraft. Ni-Mn-Ga ferromagnetically shape memory alloys is a promosing intelligent actuator material for spacecraft due to its fast response and large magnetic-field-induced strain. However, the proton irradiation effect and its mechanism of Ni-Mn-Ga alloys are still unknown. In present study,the sedimentary model of energy and mass in the process of irradiation is to be set up, and the evolution of electronic structure, atomic structure, atomic local structure and defect structure of irradiated Ni-Mn-Ga alloys are systematically investigated, and the trinsic reason of the irradiation influence on magnetic properties is revealed. The thermodynamic model for the martensitic transformation under proton irradiation will be established, and the martensitic transformation of irradiated Ni-Mn-Ga alloys is to be investigated, and the relationship among irradiation parameters, microstructure, martensitic transformation and magnetic-field-induced strain is clarifed, and the physical nature of the effect of proton irradiation on magnetic induced strain characteristics is revealed. This study is not only enriche the martensitic transformation theory, but also provides the theoretical basis of design and reliability evaluation for the application of Ni-Mn-Ga in aerospace.

质子辐照是影响航天器及其构件寿命和可靠性的重要因素。Ni-Mn-Ga铁磁记忆合金兼具快响应和大磁感生应变，在长寿命航天器中极具应用潜力，但Ni-Mn-Ga合金的质子辐照效应及微观机制尚未见报道。本研究在建立Ni-Mn-Ga合金质子入射过程中能量与质量沉积模型基础上，查明质子辐照后合金的电子结构、原子结构、原子局域结构以及缺陷结构等微观结构演化规律，揭示质子辐照影响磁学性能的物理本质；构建辐照作用下马氏体相变热力学与动力学模型；研究质子辐照Ni-Mn-Ga合金的马氏体相变行为，探明辐照参量-微观结构-马氏体相变-磁感生应变之间定量关系，揭示质子辐照影响磁感生应变的物理本质。这些研究不仅可以丰富马氏体相变基础理论，而且为Ni-Mn-Ga合金在空间领域应用设计及可靠性评估提供技术支撑。

空间射线辐照是使役条件下航天器材料及器件性能衰减的重要因素。空间射线主要由高能质子组成，特征能量在keV~MeV范围。Ni-Mn-Ga铁磁记忆合金是一种Heusler型合金，呈现独特的磁感生应变行为，兼具有快响应(~kHz)、大输出应变(~10%)、高输出应力(~7MPa)等特性，在大口径二维快速转向反射镜等航天器系统中有巨大潜在应用价值。本研究从质子辐照Ni-Mn-Ga铁磁记忆合金中能量与质量传递物理模型入手，查明合金质子辐照后多尺度微观结构特征，研究质子辐照对马氏体相变的影响规律，阐明马氏体相变辐照效应的微观机制，建立辐照参量—微结构—相变—磁感生应变之间的内在联系，揭示Ni-Mn-Ga铁磁记忆合金质子辐照效应的物理本质，对于Ni-Mn-Ga合金在长寿命航天器中的应用设计及可靠性评估具有现实指导意义。母相Ni-Mn-Ga薄膜经120keV质子辐照，当注量低于1×1015p/cm2时，相结构不发生改变；升高注量至1.0×1016p/cm2，薄膜局部区域发生辐照诱发马氏体相变，形成调制结构正交7M马氏体，变体间呈(20-2)Ι型孪晶关系，变体内部亚结构为微孪晶。7M马氏体Ni-Mn-Ga薄膜经120keV、2.0×1016p/cm2质子辐照后，薄膜中形成非调制NM马氏体；经3MeV、5×1015p/cm2质子辐照发生马氏体变体再取向；增加注量至2×1016p/cm2，马氏体变体再取向继续发生，同时在局部区域形成NM马氏体；继续增大注量，NM马氏体体积分数增多，当注量为5×1016 p/cm2时，在薄膜中出现少量尺寸约为30~120 nm的非晶微区。Ni-Mn-Ga薄膜经质子辐照后，马氏体正逆相变温度随注量的增加而升高，其居里温度则发生显著降低。马氏体态薄膜在120keV质子辐照时，随质子注量增加其居里温度均呈线性降低；经3MeV、5×1015p/cm2质子辐照后，居里温度迅速降低，继续增加质子注量居里温度保持稳定。120keV质子辐照Ni-Mn-Ga薄膜后，马氏体的饱和磁化强度先增加后下降。这些研究不仅可以丰富马氏体相变基础理论，而且为Ni-Mn-Ga合金在空间领域应用设计及可靠性评估提供技术支撑。共发表SCI论文9篇，授权2项国家发明专利，培养博士生4名，硕士4名。