Effect of dissolved hydrogen on electron transport in nickel–chromium alloys
摘要:
The thermoelectric power and electrical resistance of Ni0.95Cr0.05Hc alloys (0less than or equal tocless than or equal to0.96), obtained by high pressure hydrogenation, have been measured between 80 and 300 K. The electrical resistance of two other Ni1-xCrx-H alloys (x=0.025 and 0.11) has been measured in the range from 4 to 300 K. The absorbed hydrogen acting as electron donor induces qualitative changes in the behavior of both properties. The negative temperature coefficient of resistance over a wide T-range and the non-monotonic course of the thermoelectric power are attributed to a Kondo-like effect, i.e., spin-flip scattering of electrons on magnetic moments localized at the chromium atoms. (C) 2002 Elsevier Science B.V. All rights reserved.
have been synthesized on graphene sheets via a facile chemical reduction route, which show the highest catalytic activity reported to date for noble-metal-free catalysts for hydrogenevolution from the hydrolysis of ammoniaborane with a turnover frequency value as high as 66.7 mol H2 (mol metal min)−1.
已通过一种简便的化学还原途径在石墨烯片上合成了用Mo掺杂剂改性的Ni纳米颗粒,该纳米颗粒显示了迄今为止报道的无贵金属催化剂从氨硼烷水解产生氢气的最高催化活性,其周转频率值为高达66.7 mol H 2(最小金属mol)-1。
Lattice parameter variation and its effect on precipitation behaviour of ordered Ni2(Cr,Mo) phase in Ni-Cr-Mo alloys
作者:A. Verma、J.B. Singh、S.D. Kaushik、V. Siruguri
DOI:10.1016/j.jallcom.2019.152195
日期:2020.1
Ni-Cr-Mo based superalloys often precipitate out particles of an ordered Ni-2(Cr,Mo) phase in the gamma-matrix, whose kinetics varies with composition of alloys. Precipitation of the Ni-2(Cr,Mo) phase involves a change in the unit cell from cubic to orthorhombic structure. Lattice misfit strains associated with such cubic to non-cubic transformations significantly affect precipitation behaviour. In the present work, a series of Ni-Cr-Mo alloys have been investigated in order to study the effect Cr and Mo solutes on lattice parameters of disordered as well as ordered phases, and its manifestation on precipitation behaviour of the Ni-2(Cr,Mo) phase. Lattice parameters have been determined on the basis of Rietveld refinement of x-ray and neutron diffraction data obtained from different alloys in solution treated as well as aged conditions. Present results have shown that lattice misfit strains in these alloys increases monotonously with the increase of Mo/Cr ratio, which significantly affects the precipitation behaviour of the ordered Ni-2(Cr,Mo) phase. (C) 2019 Elsevier B.V. All rights reserved.
Experimental and Theoretical Investigation on Phase Formation and Mechanical Properties in Cr–Co–Ni Alloys Processed Using a Novel Thin-Film Quenching Technique
The Cr-Co-Ni system was studied by combining experimental and computational methods to investigate phase stability and mechanical properties. Thin-film materials libraries were prepared and quenched from high temperatures up to 700 degrees C using a novel quenching technique. It could be shown that a wide Al solid solution region exists in the Cr-Co-Ni system. To validate the results obtained using thin-film materials libraries, bulk samples of selected compositions were prepared by arc melting, and the experimental data were additionally compared to results from DFT calculations. The computational results are in good agreement with the measured lattice parameters and elastic moduli. The lattice parameters increase with the addition of Co and Cr, with a more pronounced effect for the latter. The addition of similar to 20 atom % Cr results in a similar hardening effect to that of the addition of similar to 40 atom % Co.
Effect of chemical disorder on Griffiths phase in weak itinerant ferromagnetic Ni92−xCuxCr8 alloy