Magnetron Fenicoti, Nimnga Shape Memory Alloy Organizational Structure And Magnetic Properties Of Study

In this paper, FeNiCoTi magnetic shape memory alloys(MSMA) were prepared by means of Rapid Solidification Technology (copper-mold vacuum suction casting) and shape memory effect and microstructure were investigated by differential scanning calorimeter(DSC), Vibrating Sample Magnetometer(VSM), X-ray diffraction(XRD), scanning electron microscope(SEM), etc. Martensitic transformation, structure, morphology and magnetic properties of different composition of FeNiCoTi alloys by different heat treatment were studied. The results show:1. The structure of FeNiCoTi alloys is influenced by heat treatment. Fe₅₂Ni₂₉Co₁₅Ti₄(Ni/Co=1.933)alloy treated by 700℃aging for 3h and quenching in liguid nitrogen is characteristic of obvious preferred orientation.2. The morphology of FeNiCoTi alloys is influenced by composition and heat treatment. Fe₅₂Ni₂₇Co₁₇Ti₄ alloy (Ni/Co=1.588) treated by 700℃aging for 3h and quenching in liquid nitrogen is characteristic of thin plate martensite, and obtains lots of twins. The appearance of twins is favor of realization of magnetic shape memory effect.3. With increasing the ratio of Ni/Co, martensitic stability and martensitic transformation temperature decreases. Fe₅₂Ni₂₉Co₁₅Ti₄ alloy treated by 600℃aging for 3h and quenching in water is characteristic of austenite.4. The microhardness of FeNiCoTi alloys is influenced by structure. The microhardness of martensite is higher than austenite. Microhardness of the alloys which are treated by quenching in liquid nitrogen increases.5. There are two stage transformation processes during heating. After heat treatment, the uniformity of microstructure is improved due to very high cooling rate. The microstructure of Ni₄₈Mn₃₃Ga₁₉ alloy is characteristic often-layered martensite transformed from austenite after heat treatment. The microhardness of NiMnGa alloy is increased by rapid solidification technology. 6. With increasing the ratio of Ni/Co, the microstructure of FeNiCoTi alloys is characteristic of face-centered cubic austenite transforms from body-centered tetragon rnartensite. So the susceptibility is also changed. After 600℃aging, Fe₅₂Ni₂₄Co₂₀Ti₄,Fe₅₂Ni₂₅Co₁₉Ti₄ and Fe₅₂Ni₂₇Co₁₇Ti₄ alloys are characteristic of martensite. Fe₅₂Ni₂₉Co₁₅Ti₄ and Fe₅₂Ni₃₂Co₁₁ Ti₄ alloys are characteristic of austenite. Martensite easily achieves saturated magnetization compared with austenite. With increasing the ratio of Ni/Co (H=16000G), saturation magnetization and K₁ decrease. The value of martensite is higher than austenite.7. The saturation magnetization of as-casted NiMnGa alloy is lower. The saturation magnetization of NiMnGa alloys annealing in 800℃is improved.8. The saturation magnetization and K₁ of FeNiCoTi alloys are larger than NiMnGa alloys. Large saturation magnetization and K₁ are in favor of magnetic shape memory effect.