Ni_(54)Mn_(25.1)Ga_(20.9) ferromagnetic shape memory thin film was deposited onto Al foil using r.f.magnetron sputtering technique.The crystallization behavior of the film was investigated by XRD and DSC.The activation energy of crystallization of the film was calculated by Kissinger's method.The results show that the crystallization temperature of Ni_(54)Mn_(25.1)Ga_(20.9) free-standing thin film in martensite state is 372 ℃,and the activation energy of crystallization is about 191.9 kJ·mol-1.
A series of ZnO nanostructures such as nanowires,nanobelts,nanocombs and mesoporous nanoballs were fabricated by a simple carbon reduction method without catalyst.The morphologies and microstructures of all samples were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and energy dispersive X-ray spectroscopy.The results indicate that different deposition temperatures have great impact on different shapes of ZnO nanostructures.The growth mechanisms of these ZnO nanostructrues suggest that,by controlling the experiment parameters,different morphological configurations nanostructures can be fabricated.
CAI Wei,and LIU Wencheng School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China
The microstructure,phase transformation,compression property and strain recovery characteristics of equiatomic Ru-Nb high temperature shape memory alloy were investigated by means of optical microscope,X-ray diffraction(XRD),differential scanning calorimetry(DSC),compression tests and transmission electron microscopy(TEM).When cooling the alloy specimen from high temperature to room temperature,β(parent phase)→β'(interphase)→β″(martensite) two step phase transformation occurs.The microstructure at room temperature shows regularly arranged band morphology with the monoclinic crystal structure.The twinning relationship between the martensite bands was determined to be(101) Type I.Reorientation and of the martensite bands inside the variant and dislocation were found during compression at room temperature.The maximum complete recovery strain is about 1.5%.
GAO Xin,CAI Wei,and GAO Zhiyong School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China
