The copper-based friction material with Cr–Fe particles was prepared using the hot pressing powder metallurgy sintering process. Effects of Cr–Fe particles content on the microstructure formation and the friction/wear property of copper-based friction material were investigated. The addition of Cr–Fe powder could effectively modify the bonding status between the hard phase and the matrix. The bonding strength between the hard phase and the matrix increased with increasing content of Cr–Fe powders in the range of 0–11 wt-%. With increasing content of Cr–Fe powders, the hardness of the copper-based friction material increased gradually. When the content of Cr–Fe was 11 wt-%, the copper-based friction material had the best combination of coefficient of friction, hardness and wear capacity.

Hydrate-based technologies have excellent application potential in gas separation, gas storage, transportation, and seawater desalination, etc. However, the long induction time and the slow formation rate are critical factors affecting the application of hydrate-based technologies. Micro-nano bubbles (MNBs) can dramatically increase the formation rate of hydrates owing to their advantages of providing more nucleation sites, enhancing mass transfer, and increasing the gas–liquid interface and gas solubility. Initially, the review examines key performance MNBs on hydrate formation and dissociation processes. Specifically, a qualitative and quantitative assembly of the formation and residence characteristics of MNBs during hydrate dissociation is conducted. A review of the MNB characterization techniques to identify bubble size, rising velocity, and bubble stability is also included. Moreover, the advantages of MNBs in reinforcing hydrate formation and their internal relationship with the memory effect are summarized. Finally, combining with the current MNBs to reinforce hydrate formation technology, a new technology of gas hydrate formation by MNBs combined with ultrasound is proposed. It is anticipated that the use of MNBs could be a promising sustainable and low-cost hydrate-based technology.

Microstructure is one of the vital factors that determine the mechanical properties of magnesium (Mg) alloys. However, traditional microstructure characterization methods hardly satisfy the needs of tracking the morphological evolution of Mg alloys. With the rapid development of computer simulation, using the phase-field method to simulate the evolution of microstructures in Mg alloys has become the new norm. This article provides a review of the applications of the phase-field method in Mg alloys. First, classic phase-field models and the derived multi-phase and polycrystalline phase-field models are reviewed, then a review of the twin and solid-state phase transition phase-field models was undertaken, and the research progress of phase-field simulation in the solidification, recrystallization, and solid-state phase transformation of Mg alloys, were gradually introduced. In addition, unresolved problems of phase-field simulation were summarized, and the possible direction of future studies on phase-field simulation in Mg alloys field were discussed.

The digital speckle correlation method (DSCM) is introduced to solve the challenging problems in the related geometric measurement. Theoretical calculations of strain are deduced using the DSCM. Corresponding strains along $x$ and $y$ directions are obtained from uniaxial tension experiments and digital speckle measurements, using the VCM nondeep drawing multilayer sheet, the VCM deep-drawing multilayer sheet, clad films, nondeep drawing substrate, and deep-drawing substrate sheet as the targeted experimental objects. The results show that the maximum strains along the $x$ direction of the VCM nondeep drawing multilayer sheet, the VCM deep-drawing multilayer sheet, clad film, nondeep drawing substrate, and deep-drawing substrate sheet are 68.473%, 48.632%, 91.632%, 50.784% and 40.068%, respectively, while the maximum strains along the $y$ direction are $-2.657\%$, $-15.381\%$, 2.826%, $-9.780\%$ and $-7.783\%$, respectively. The mechanical properties of the VCM multilayer sheet are between those of the substrate and clad film, while mechanical properties of the VCM deep-drawing multilayer sheet are superior to those of the VCM nondeep drawing multi-layer sheet.

The microstructure evolution and interface characteristics of a directionally solidified Ti-43Al-3Si (at.%) alloy in an alumina (Al₂O₃) crucible with new Y₂O₃ skull-aided technology were investigated. The Y₂O₃-skull that is in contact with the TiAl-melt is relatively stable, which results in a more controlled reaction between the skull and the melt than in the case of an Al₂O₃ crucible is used. A thin reaction layer was formed between the mould and the melt through mutual diffusion. The layer thickness increased with increasing reaction time. The thickness of this layer was less than 80 μm for reaction times up to 5800 s. Y₂O₃ particles were not found in the specimen because the mould coating was prepared with fine Y₂O₃ powder without a binder, which prevented the Y₂O₃ particles splitting from the coating as a consequence of thermal physical erosion. The oxygen content of the TiAl-alloy increased with increasing reaction time. The total oxygen content of the solidified specimen was less than that of the specimen solidified in the Al₂O₃ crucibles. This new Y₂O₃ skull-aided technology is expected to improve the surface quality of TiAl-alloys and reduce the reaction between the crucible/mould and molten TiAl alloys during directional solidification processing with longer contact times.