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ABSTRACT: A systematical study of substitution of Ge for Ni, Fe, and Ga in the non-stoichiometric NiFeGa alloys was performed in this work. The effect of Ge addition on the structure and martensitic transformation in NiFeGa alloys was investigated by an optical microscope, X-ray diffraction, and differential scanning calorimeters. The results show that the transformation temperatures decrease almost linearly with increasing Ge content in all the three types from higher than 100 down to −90 °C and even lower. The decreases in rate of the martensitic transformation temperatures are different for the three cases. It is large for Ni substituted by Ge, slow for Ga and intermediate for Fe. The determined relationship will be significant for designing a suitable NiFeGa alloy with a required martensitic transformation temperature for application at specific temperature.
Materials Science and Engineering: A.
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ABSTRACT: An incomplete thermal cycle upon heating in a shape memory alloy (arrested at a temperature between A s and A f ) induced a kinetic stop in the next complete thermal cycle. The kinetic stop temperature is closely related to the previous arrested temperature. This phenomenon is named temperature memory effect (TME). In this article, the TME in two-way shape memory TiNiCu and TiNi springs was investigated by performing either a single incomplete cycle, or a sequence of incomplete cycles. N points of temperatures could be memorized if N times of incomplete cycles on heating were performed with different arrested temperatures in a decreasing order. The capability is enhanced by performing repetitive incomplete cycles with the same temperature, and the TME can be eliminated by appropriate complete transformation cycle. The TME is originated from the relaxation of both the strain energy between martensite and coherent strain between parent phase and martensite. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/43242/1/10853_2005_Article_5908.pdf
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ABSTRACT: The surface of ZnO and anatase TiO2 nanocrystals was modified by PMMA through γ radiation. The modified nanocrystals were investigated with photoluminescence (PL) and Fourier transform infrared (FTIR) spectra. A stable blue luminescence peak (∼420 nm) can be observed for the modified ZnO and anatase TiO2 nanocrystals. The intensities of luminescence of the modified ZnO and anatase TiO2 in aqueous solution are very stable, even unchanged after storage time of one month.
Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 250:196-200. · 1.21 Impact Factor
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ABSTRACT: The effect of Ge addition on the microstructure, transformation temperatures and mechanical properties of (Ni56.5Fe17Ga26.5)100−xGex ferromagnetic shape memory alloys was investigated. With the increase of Ge content in these alloys the martensitic transformation temperatures decrease almost linearly from higher than 100 °C down to −70 °C or even lower that is attributed to the change of the electron concentrations of the Ni–Fe–Ga(Ge) alloys. The addition of Ge also significantly enhances the compression strength and the ductility of the alloys. The determined relationships between transformation temperatures and the mechanical properties and the Ge content will be useful for designing a suitable Ni–Fe–Ga(Ge) alloy device with a required martensitic transformation temperature and optimized mechanical property.
Journal of Alloys and Compounds.
