Aluminum foam sandwich (AFS) structure materials have drawn much attention due to their unique structural and functional properties. However, the use of AFS materials as an attractive candidate for some applications was limited. In this work, AFS was fabricated by the brazing method, using Al-Si-based alloy, aluminum foam and steel plates as filler, matrix and panels, respectively. The microstructures of the soldered interfacial region, elemental distributions and phase identification were determined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The diffusion behavior of Si, Al, Fe and Cr was investigated. The effect of brazing time on the shear strengths of soldered joints was also analyzed. The results showed that the microstructures of joints were changed on increasing the brazing time. When the brazing time was 5 min, the solder started melting, which led to low shear strength. When increasing the brazing time to 10 min, the shear strength reached the peak value of 6.26 MPa due to the formation of a layer plate structure in the joints. When further increasing the brazing time, a number of Al/Fe intermetallic compound were formed in the joints, leading to a decrease of the shear strength due to the formation of brittle phase.

Titanium alloys are widely used in various structural materials due to their lightweight properties. However, the low wear resistance causes significant economic losses every year. Therefore, it is necessary to implement wear-resistant protection on the surface of titanium alloys. In this study, four types of in situ composite ceramic coatings with two-layer gradient structures were prepared on a Ti-6Al-4V (TC4) substrate using laser cladding. In order to reduce the dilution rate, a transition layer (Ti-40SiC (vol.%)) was first prepared on TC4 alloy. Then, a high-volume-fraction in situ composite ceramic working layer (Ti-xFe-80SiC (vol.%)) with different contents of Fe-based alloy powder (x = 0, 5, 10 and 15 vol.%) was prepared. The working surface of Ti-40SiC (TL) exhibited a typical XRD pattern of Ti, TiC, Ti₅Si₃, and Ti₃SiC₂. In comparison, both Ti-80SiC (WL-F0) and Ti-5Fe-80SiC (WL-F5) exhibited similar phase compositions to the TL coating, with no new phase identified in the coatings. However, the TiFeSi₂ and SiC phases were presented in Ti-10Fe-80SiC (WL-F10) and Ti-15Fe-80SiC (WL-F15). It is proven that the addition of the Fe element could regulate the in situ reaction in the original Ti-Si-C ternary system to form the new phases with high hardness and good wear resistance. The hardness of the WL-F15 (1842.9 HV₁) is five times higher than that of the matrix (350 HV₁). Due to the existence of self-lubricating phases such as Ti₅Si₃ and Ti₃SiC₂, a lubricating film was presented in the WL-F0 and WL-F5 coatings, which could block the further damage of the friction pair and enhance the wear resistance. Furthermore, a wear-transition phenomenon was observed in the WL-F10 and WL-F15 coatings, which was similar to the friction behavior of structural ceramics. Under the load of 10 N and 20 N, the wear volume of WL-F15 coating is 5.2% and 63.7% of that in the substrate, and the depth of friction of WL-15 coating is only 14.4% and 80% of that in the substrate. The transition of wear volume and depth can be attributed to the wear mechanism changing from oxidation wear to adhesive wear.

Ameliorating the high-temperature performance of cast Al-Si alloys used as engine components is essential. The effects of different T6 heat-treatment processes on the microstructure and mechanical properties of cast Al-Si-Cu-Mg-Ni-Cr alloys were investigated in the present study. The results demonstrate that, under the optimal solution treatment conditions of 500 °C for 2 h and 540 °C for 4 h, the T-Al₉FeNi phase was present in the alloy, and the roundness of primary Si and the aspect ratio of eutectic Si in the alloy reached valley values of 1.46 and 2.56, respectively. With increasing ageing time at 180 °C, the tensile strength significantly improved, while the microhardness first increased and then decreased. When the ageing time was 4 h, microhardness reached a peak value of 155.82 HV. The fracture characteristics changed from quasi-cleavage to the coexistence of quasi-cleavage and dimples. After heat treatment, the high-temperature tensile properties of the alloy improved, which is a significant advantage compared to the as-cast alloy. The stable Al₃Ni and Al₉FeNi phases inhibited the cracking of the alloy at 350 °C.

Cu–9Ni–6Sn alloys have received widespread attention due to their good mechanical properties and resistance to stress relaxation in the electronic and electrical industries. The hot compression deformation behaviors of the Cu–9Ni–6Sn–0.3Mn–0.2Zn alloy were investigated using the Gleeble-3500 thermal simulator at a temperature range of 700–900 °C and a strain rate range of 0.001–1 s⁻¹. The microstructural evolution of the Cu–9Ni–6Sn alloy during hot compression was studied by means of an optical microscope and a scanning electron microscope. The constitutive equation of hot compression of the alloy was constructed by peak flow stress, and the corresponding 3D hot processing maps were plotted. The results showed that the peak flow stress decreased with the increase in the compression temperature and the decrease in the strain rate. The hot deformation activation energy was calculated as 243.67 kJ/mol by the Arrhenius equation, and the optimum deformation parameters for the alloy were 740–760 °C and 840–900 °C with a strain rate of 0.001~0.01 s⁻¹. According to Deform-3D finite element simulation results, the distribution of the equivalent strain field in the hot deformation samples was inhomogeneous. The alloy was more sensitive to the deformation rate than to the temperature. The simulation results can provide a guideline for the optimization of the microstructure and hot deformation parameters of the Cu–9Ni–6Sn–0.3Mn–0.2Zn alloy.