Surface textures have various applications, such as friction/wear reduction and light absorbing enhancement. Deformation-based surface texturing has the potential of economically creating micro-scale surface textures over a large surface area. A novel desktop surface texturing system is proposed for efficiently and economically fabricating microchannels on the surface of thin sheet material for microfluid and friction/wear reduction applications. Both the experimental and numerical studies were employed to analyze the problems of the flatness of the textured sheet, the uniform of the channel depth and pile-ups built up during the surface texturing process. The results demonstrated a clear relationship between relative velocity of the upper and lower rolls and the flatness of the textured sheet and the final profile of the microchannels.

The effect of differential roller temperature (DTR) (low and high roller temperature difference: 60 and 180 K) on the microstructure evolution, deformation mechanism, and mechanical properties were investigated in a commercial AZ31B alloy sheet. Compared with the LDTR sample, a considerable shear strain ( 0.4) in the HDTR sample led to a multiple-twinning system, especially the formation of contraction twins (CTWs) and double twins (DTWs). After annealing, the HDTR-annealing (HDTR-A) sample achieved an excellent ductility (∼33.6%) as a result of a higher recrystallization fraction (∼71.75%) and more optimized texture component (max basal texture intensity decrease from 36.13–8.06). GRAPHICAL ABSTRACT IMPACT STATEMENT A new method, differential temperature rolling, was used in AZ31B Mg alloy to induce multiple-twinning systems, which strongly influences the recrystallization mechanism and texture evolution, leading to a high ductility.

In order to solve the problem of insufficient convective heat transfer of uniaxial stirred melt, the temperature field and shear rate of melt under planetary stirring were studied based on CFD simulation. The microstructure and properties of this technology were also experimentally studied. The results show that compared with the uniaxial stirring semi-solid technology, the convective heat transfer ability of aluminum alloy, semi-solid slurry in planetary stirring mode is stronger. In addition, its temperature field can be reduced to the semi-solid range faster and more evenly, which is conducive to a large number of nucleation and improves the nucleation rate. The temperature difference of the whole melt is small, so the preferred direction growth and uniform growth of dendrites are avoided, and the morphology is improved. Properly increasing the revolution and rotation speed of the stirring shaft can refine the grains of semi-solid aluminum alloy parts, improve the grain morphology, and improve the tensile strength. The planetary stirring semi-solid process is very suitable for rheological high-pressure casting.

The classic molecular dynamics (MD) simulation approach has been used to investigate the microstructure change in polycrystalline magnesium (Mg) during compressive deformation at various temperatures. At low temperatures, there exists a competition between the sliding of Shockley partial dislocation (SPD) and perfect dislocation. Abundant dislocation behaviors such as dislocation bundle and double cross slipping are observed. With a temperature increase, the dislocation sliding is hindered by the newly formed grain boundaries (GBs). The grain reorientation should be the compensatory mechanism for plastic deformation at high temperatures. Furthermore, dynamic recrystallization (DRX) is found at the highest temperature investigated. For all the temperature cases studied, twinning is unsensitive against applied compressive stress. The results of this work may help to understand the temperature effect on the mechanism in polycrystalline Mg under compressive deformation.

The effects of secondary rolling on the microstructure evolution and mechanical properties of Al/Mg/Al clad sheets have been investigated. The results indicate that a double-layer intermetallic compound (Mg₂Al₃ and Mg₁₇Al₁₂) forms and sandwiches the MgO film during the first rolling and annealing, while the sandwich structure shows a low peel strength owing to the intrinsic brittleness of intermetallic. However, a secondary rolling leads to a shear-induced breakage of the sandwich structure, whereupon the peel strength significantly increases from 1.3 N/mm to 12.7 N/mm on account of an effective bonding of the Mg/Al interface. The secondary rolling not only eliminates the influence of MgO on the interface, but also improves the bonding strength of the interface. Furthermore, the clad sheet can obtain an excellent elongation (21%) and remain of high interfacial strength (∼12 N/mm) after the recovery annealing.

Using molecular dynamics (MD) simulation, the strain-induced phase transitions in pure body-centered-cubic (bcc) iron (Fe) thin films containing twin boundaries (TBs) with different TB fractions and orientations are studied. Two groups of bcc thin films with different TB-surface orientation relationships are designed. In film group 1, the (112) [ $11\overline{1}$ ] TBs are perpendicular to the ( $11\overline{1}$ ) free surfaces, while the (112) [ $11\overline{1}$ ] TBs are parallel to the free surfaces in film group 2. We vary the TB numbers inserted into the films to study the effect of TB fraction on the phase transition. Biaxial strains are applied to the films to induce the bcc to close packed (cp) phase transition. The critical strain, at which the first phase transition takes place, decreases with the TB fraction increase in film group 1 with a perpendicular TB-surface orientation, while such a relationship is not observed in film group 2 with parallel TB-surface orientation. We focus on the free surface and TB as the nucleation positions of the new phase and the afterward growth. In addition, the dynamics of the phase transition is discussed. This work may help to understand the mechanism of phase transition in nanoscale or surface-dominant systems with pre-existing defects.