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In the field of electrocatalysis, most of the electrodes have the problem of poor mechanical properties, which leads to the electrode can not be used on a large scale. At present, most bulk electrodes are used to study their mechanical properties due to their unique phase composition distribution and facile fabricate methods. But their novel properties in the field of electrocatalysts have not been fully developed. Multi-element bulk electrodes not only diversified the electronic states, but also build complex surface morphology by different dissolution rate between multi-phase distribution. In this paper, we synthesized the FeNiMo bulk electrode for oxygen evolution reaction (OER) with two-phase coexistence of Mo-doped face center cubic phase (FCC) and Mo-rich intermetallic compound (IMC) phase. During cyclic voltammetry activation, the surface reconstruction of Mo-rich IMC phases generated by ion leaching leaves Fe–Ni pore structures with more active area, which enhances OER performance. Meanwhile, the electron states get more diverse on the surface of remaining FCC phases due to Mo doping, which provides more suitable sites for four-step OER process. The FeNiMo electrode shows an ultra-low overpotential of 212 mV and 293.4 mV at a current density of 10 mA cm−2 and 100 mA cm−2, respectively. Moreover, it can maintain stability at 100 mA cm−2 for up to 72 h. This work provides a strategy for studying the relationship between phase composition and electrochemical performance of alloy bulk electrodes.

The influence of different Mg concentrations on the mechanical properties and microstructure of an Al–Li alloy was studied. The highest Mg content was up to 1.1 wt.%. To the best of the authors knowledge, alloys with such a high Mg content has not been reported in the literature. The mechanical properties, yield strength and elongation at failure, of all of the alloys were investigated by tensile tests. Characterisation of the precipitates by analysing the dark field images and related diffraction patterns revealed that precipitation of the T1 phase (Al2CuLi) was retarded by high (1.1 wt.%) Mg concentration. We hypothesized that a competition between the precipitation of T1 phase and S' phase in high Mg containing alloy caused sluggish precipitation phenomenon and associated strengthening.

The influence of Ag on the microstructure evolution of an aged Al–Cu–Li–Mg alloy was studied. The coarse Cu-rich precipitates containing Ag and Mg were found during the whole ageing process of Al–Cu–Li–Mg–Ag alloy. Besides, Ag addition in the Al–Cu–Li–Mg alloy accelerates the hardness value reduction of the overaged alloy. When the alloy was over heat-treated, more coarse Cu-rich phases containing Ag and Mg are presented at the grain boundaries. These discrete coarse precipitates accelerate the hardness reduction of the overaged alloy.

The effects of solution time and cooling rate on microstructures and mechanical properties of 2219 Al alloy for a larger spun thin-wall ellipsoidal head are investigated. It is found that the Al2Cu phases are greatly affected by the solution time. The content of Al2Cu phases first decreases and then stabilizes with increasing the solution time. Moreover, the effects of solution time on the transformation of precipitates are obvious. As the solution time is increased from 35 min to 60 min, almost all the precipitates transfer from GP zones to θ′′ phases. When the solution time is further increased to 110 min, some θ′ phases appear. Meanwhile, the size of θ′′ phases increases, while the density of θ′′ phases drops. These microstructure changes greatly influence the mechanical properties, i.e., the hardness and tensile strengths first increase and then slightly decrease with the continuous increase of the solution time. In addition, if the cooling rate is decreased, the precipitation of coarse equilibrium θ phases is enhanced, but the precipitation of strengthening phases (θ′′, θ′) is restricted. It significantly deteriorates the mechanical properties. Based on the comprehensive analysis, the suitable solution time and cooling method are about 60 min and water cooling.

The tensile properties and corrosion behaviours of an ageing Al-1.7 Cu-4.0 Li- 0.4 Mg alloys (in at. %) with or without 0.3 Zn addition were investigated by detailed microstructure evolution using TEM and STEM. Herein, the Zn addition to the Al-1.7 Cu-4.0 Li- 0.4 Mg ageing alloy is determined as a convincing approach to optimising the strength-corrosion resistance balance. With Zn addition, the increasing quantity of T1 phase in grain led to the increase of the tensile property of the Al-1.7 Cu-4.0 Li- 0.4 Mg alloy. While the studied alloy with Zn addition possessed preferable corrosion resistance in respect of intergranular corrosion (IGC) depth reducing. Moreover, the emergence of Zn elements in the coarse phases at grain boundary (GB) may decrease the potential differences between the precipitates at GB and free precipitation zone (PFZ), which could increase corrosion resistance. Keywords: Al-1.7 Cu-4.0 Li- 0.4 Mg alloy, Zn addition, Tensile properties, Corrosion behaviours, Microstructure characteristics, Electrochemical features