(台州学院 物理与电子工程学院，台州 318000)
摘 要: 采用定向凝固方法制备了Ni47Mn32Ga21多晶合金，通过XRD谱和金相照片研究合金的结构，通过对合金磁化强度与温度关系、电阻与温度关系、磁化曲线和磁感生应变曲线的测量分析，研究了合金的相变、磁化特性及磁感生应变特性。结果表明：Ni47Mn32Ga21合金在室温(298K)时为四方结构马氏体相，晶格参数a=b=0.593 8 nm，c=0.553 1 nm。合金的马氏体相变起始温度Ms和终止温度Mf分别为309 K和295 K，逆马氏体相变起始温度As与终止温度Af 分别为306 K和319 K，居里温度TC为365 K。室温无压力下，Ni47Mn32Ga21合金有较好的双向可恢复磁感生应变，其饱和磁感生应变值达到−700×10−6。
关键字: Ni-Mn-Ga合金；定向凝固；马氏体相变；形状记忆合金；磁感生应变
polycrystalline Ni47Mn32Ga21 directionally solidified alloy
（School of Physics and Electronic Engineering, Taizhou University, Taizhou 318000, China）
Abstract:Ni47Mn32Ga21 polycrystalline alloy was prepared by the directional solidification technique. The structure of the alloy were investigated using XRD and metallography methods. The phase-transformation, magnetization properties and magnetic-field-induced strains were also studied through analyzing the magnetization as a function of temperature, the resistance as a function of temperature, magnetization and magnetic field-induced strain curves. The results show that Ni47Mn32Ga21 alloy exhibits martensitic phase of a tetragonal structure with lattice parameters a=b=0.593 8 nm and c=0.553 1 nm at room temperature (298 K). The martensitic start temperature Ms and the martensitic finish temperature Mf are 310 K and 295 K, respectively. The austenitic start temperature As and austenitic finish temperature Af are 306 K and 319 K, respectively. The Curie temperature of alloy TC is 365 K. Ni47Mn32Ga21 alloy exhibits excellent free recoverability of the magnetic-field-induced strains at room temperature without external stress. The saturated value of magnetic-field-induced strain reaches −700×10−6.
Key words: Ni-Mn-Ga alloy; directional solidification; martensitic transformation; shape memory alloy; magnetic-field- induced strain
