Stochastic heterogeneous microstructures are widely applied in structural and functional materials, playing a crucial role in determining their performance. X-ray tomography and focused ion beam serial sectioning are frequently used methods to reconstruct three-dimensional (3D) microstructures, yet are demanding techniques and are resolution-limited. Here, a high-throughput multi-stage 3D reconstruction method via distance correlation functions is developed using a single representatively large-sized 2D micrograph for stochastic microstructures, and verified by X-ray micro-tomography datasets of isotropic and anisotropic solid oxide fuel cell electrodes. This method provides an economic, easy-to-use and high-throughput approach for reconstructing stochastic heterogeneous microstructures for energy conversion and storage devices, and can readily be extended to other materials.

High-temperature catalytic and transport properties of porous ionic–electronic conducting materials (MIECs) are vital for device-level performance and are sensitive to microstructure, however they are indirectly characterized using dense MIECs with simple geometry. The structure–property relationship can be misinterpreted, as the fabrication procedures and microstructures of the dense MIECs are different from those of the porous MIECs. Here, the distribution of characteristic times (DCT) is proposed to resolve chemical relaxation (CR) kinetics in porous MIECs. The peak in a DCT spectrum has a clear physical origin, with its integral area being the fractional volume involved. In contrast to previous treatments that assume surface exchange-limited kinetics, the DCT spectra of porous La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF) show that gaseous oxygen diffusion can dominate the CR kinetics in 0–40 percent volume, depending on the sintering temperature of the sample. The surface exchange coefficient and its thermal activation energy are much lower than those of the dense bulk LSCF. These findings indicate a different catalytic mechanism on the internal surface of porous LSCF, compared to in the dense bulk material. The DCT approach opens up a way to reveal the CR kinetics in porous MIECs, and can readily be extended from e⁻/O²⁻ to e⁻/H⁺ and e⁻/H⁺/O²⁻ conducting oxides.

In order to improve the wear resistance of carburised M50NiL steel, the surface layer was deposited with Ti coating by magnetron sputtering and then plasma nitrided for 2 h with hollow cathode equipment. The influence of nitriding temperature (750, 800 and 850°C) on microstructure and mechanical properties of the coating were investigated. Results show that the coating of specimen 750 containing Ti-based-nitrides possesses higher nanohardness (13.769 ± 0.738 GPa) than the carburised layer (7.695 ± 0.338 GPa) and the load bearing capacity reaches 18 N due to the supporting carburised layer. The friction coefficient and wear rate of the specimen 750 decrease 23.1 and 72.2%, respectively, compared with the carburised specimen. The hardness and wear performance of the specimen 800 and 850 were underestimated by traditional test criterion because a loose and porous a′_C(N) layer was formed on the surface due to sputtering effect of steel hollow cathode.