Structural-thermodynamic method of phase analysis of multicomponent alloys based on the example of the Ni50Со25Мо25 alloy
作者:Y. Ustinovshikov
DOI:10.1016/j.jallcom.2014.06.060
日期:2014.11
A structural-thermodynamic method of phase analysis of multicomponent alloys is proposed. The method is based on the use of the model of pairwise interaction and experimental determination of the sign of pairwise chemical interaction and includes an electron microscopic study of microstructures above and below the temperature of phase transition ordering-phase separation for each of the diffusion couples. The method is demonstrated on the example of the Ni50Co25Mo25 alloy. It is shown what precipitates are formed in the investigated alloy over the whole temperature range of heat treatment including the liquid state. We can conclude that structural data obtained in other works, for alloys, to some extent similar in composition to the alloy studied, are far from the results obtained in the present paper. (C) 2014 Elsevier B.V. All rights reserved.
Facile synthesis of Mo–Ni particles and their effect on the electrochemical kinetic properties of La–Mg–Ni-based alloy electrodes
作者:Yuan Li、Yang Tao、Dandan Ke、Shuqin Yang、Shumin Han
DOI:10.1016/j.jallcom.2014.06.112
日期:2014.12
A simple method was developed to synthesize Mo-Ni compounds using a chemical reduction method. The compound was then added to La-Mg-Ni-based alloy electrodes in order to improve the electrochemical kinetics of the electrodes. Scanning electron microscopy and transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy showed that the as-synthesized compound consisted of nanoparticles with a chemical composition of MoNi2.5. X-ray diffraction analysis revealed that the compound mainly consisted of a MoNi3 and a Ni phase. The Mo-Ni particles were added to the La-Mg-Ni-based alloy electrode material and uniformly distributed on the alloy surface. An improvement in initial discharge capacity and high rate dischargeability (HRD) could be observed, as well as an enhancement of cycle stability. At 1500 mA/g the HRD increased by 10.2%, and the initial discharge capacity increased from 286 mA h/g to 307 mA h/g. After adding the particles to the alloy, the Mo-Ni particles showed a high electro-catalytic activity due to a charge transfer reaction on the alloy surface, thereby decreasing the charge transfer resistance and increasing the exchange current density. Consequently, the kinetics of the electrode reaction was significantly improved due to an enhancement of the electro-catalytic activity. (C) 2014 Elsevier B.V. All rights reserved.
Phase and structural transformations in the Ni65Mo20Cr15 alloy at changing the temperature of heat treatment