This paper investigates the effects of substitution of Si for Ga on the martensitic transformation behaviours in Ni-Fe-Ga alloys by using optical metallographic microscope and differential scanning calorimetry （DSC）...This paper investigates the effects of substitution of Si for Ga on the martensitic transformation behaviours in Ni-Fe-Ga alloys by using optical metallographic microscope and differential scanning calorimetry （DSC） methods. The structure type of Ni55.5Fe18Ga26.5-xSix alloys is determined by x-ray diffraction （XRD）, and the XRD patterns show the microstructure of Ni-Fe-Ga-Si alloys transformed from body-centred tetragonal martensite （with Si content x = 0） to body-centred cubic austenite （with x = 2） at room temperature. The martensitic transformation temperatures of the Ni55.sFelsGa26.5-xSi~ alloys decrease almost linearly with increasing Si content in the Si content range of x _~ 3. Thermal treatment also plays an important role on martensitic transformation temperatures in the Ni-Fe-Ga^Si alloy. The valence electronic concentrations, size factor, L21 degree of order and strength of parent phase influence the martensitic transformation temperatures of the Ni-Fe-Ga-Si alloys. An understanding of the relationship between martensitic transformation temperatures and Si content will be significant for designing an appropriate Ni-Fe-Ga-Si alloy for a specific application at a given temperature.展开更多
The influence of thermal treatment on the lux-ampere characteristics of polycrystalline films from the CdSe<sub>x</sub>S<sub>1-x</sub> solid solution obtained by the method of thermal evaporati...The influence of thermal treatment on the lux-ampere characteristics of polycrystalline films from the CdSe<sub>x</sub>S<sub>1-x</sub> solid solution obtained by the method of thermal evaporation in a vacuum has been investigated. It is shown that at low illumination intensities L μ of electrons increases with a power law μ ~ L<sup>γ</sup>, first with the exponent γ > 1, then with γ ≈ 0.5, and their concentration n almost does not change. Starting from the intensity L > 12 - 15 lx, the electron concentration increases strongly n ~ L<sup>β</sup> from β ≈ 3.0, and the parameters n and μ reach relatively high values ~(10<sup>15</sup> - 10<sup>16</sup>) sm<sup>-3</sup> and ~(150 - 200) sm<sup>2</sup>/V·s, however further, at L > 50 lx, a weak dependence of n(L) and μ(L) with β, γ < 1.0 is found. The obtained experimental results are interpreted on the basis of a model of a semiconductor film with intergranular potential barriers when the concentration and barrier mechanisms of photoconductivity operate simultaneously.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 10976007)the Fundamental Research Funds for the Central Universities (Grant Nos. ZYGX2009J046 and ZYGX2009X007)Royal Academy of Engineering-Research Exchanges with China and India Awards in UK
文摘This paper investigates the effects of substitution of Si for Ga on the martensitic transformation behaviours in Ni-Fe-Ga alloys by using optical metallographic microscope and differential scanning calorimetry （DSC） methods. The structure type of Ni55.5Fe18Ga26.5-xSix alloys is determined by x-ray diffraction （XRD）, and the XRD patterns show the microstructure of Ni-Fe-Ga-Si alloys transformed from body-centred tetragonal martensite （with Si content x = 0） to body-centred cubic austenite （with x = 2） at room temperature. The martensitic transformation temperatures of the Ni55.sFelsGa26.5-xSi~ alloys decrease almost linearly with increasing Si content in the Si content range of x _~ 3. Thermal treatment also plays an important role on martensitic transformation temperatures in the Ni-Fe-Ga^Si alloy. The valence electronic concentrations, size factor, L21 degree of order and strength of parent phase influence the martensitic transformation temperatures of the Ni-Fe-Ga-Si alloys. An understanding of the relationship between martensitic transformation temperatures and Si content will be significant for designing an appropriate Ni-Fe-Ga-Si alloy for a specific application at a given temperature.
文摘The influence of thermal treatment on the lux-ampere characteristics of polycrystalline films from the CdSe<sub>x</sub>S<sub>1-x</sub> solid solution obtained by the method of thermal evaporation in a vacuum has been investigated. It is shown that at low illumination intensities L μ of electrons increases with a power law μ ~ L<sup>γ</sup>, first with the exponent γ > 1, then with γ ≈ 0.5, and their concentration n almost does not change. Starting from the intensity L > 12 - 15 lx, the electron concentration increases strongly n ~ L<sup>β</sup> from β ≈ 3.0, and the parameters n and μ reach relatively high values ~(10<sup>15</sup> - 10<sup>16</sup>) sm<sup>-3</sup> and ~(150 - 200) sm<sup>2</sup>/V·s, however further, at L > 50 lx, a weak dependence of n(L) and μ(L) with β, γ < 1.0 is found. The obtained experimental results are interpreted on the basis of a model of a semiconductor film with intergranular potential barriers when the concentration and barrier mechanisms of photoconductivity operate simultaneously.
