In this study, a Cr₃C₂-NiCr cermet cladding layer was prepared on the surface of Q235 steel via a high-speed laser cladding method. The effects of laser power, scanning speed, and overlap rate on the microstructure, cladding quality, and interfacial elements diffusion of Cr₃C₂-NiCr/Q235 steel were studied. The results show that there was an obvious transition layer at the interface of the Cr₃C₂-NiCr cladding layer and Q235 steel, indicating that the Cr₃C₂-NiCr cladding layer had an adequate metallurgical bond with the matrix. Fe, Cr, and Ni were diffused distinctly between the cladding layer and the matrix. The height and width of the Cr₃C₂-NiCr cladding layer increased, while the dilution rate decreased with the increase in the laser power. The maximum thickness of the transition layer was about 50 μm for the 6 mm/s sample, the weld heat affected zone was smaller, and it was shown that the productivity can be effectively improved. The sample with a 40% overlap rate exhibited the best flatness. The optimal laser power, scanning speed, and overlap rate of the Cr₃C₂-NiCr/Q235 steel were 1500 W, 6 mm/s, and 40%, respectively.

The welded joints are often subjected to cyclic stresses and high-strain-rate deformation resulting in worrisome fatigue failure. Therefore, it is necessary to evaluate the fatigue resistance and cyclic deformation characteristics of these weldments. Ti–6Al–4V–0.3Fe–0.1C–0.05N–0.015H–0.2O (TC4) titanium alloy joints were produced via linear friction welding and a sound joint was obtained. It was observed that fine subgrains formed in the weld zone where the hardness became higher. The strain ratio had a strong effect on the cyclic deformation characteristics of the joint, with hysteresis loops being different at different strain ratios. However, the difference of fatigue life of the joint was small with varying strain ratios. The stress amplitude of linear friction welded TC4 joint showed essentially cyclic softening until failure at all strain ratios. Fatigue cracks initiated from the near-surface of base metal and propagated by the formation of fatigue striations together with secondary cracks.

In this study, TiB₂/7075 aluminum matrix composites were prepared via in situ synthesis. It was found that TiB₂ particles are mainly quadrate. Large TiB₂ particles (1–2 μm) agglomerate at grain boundaries, but most of the particles are on the submicron scale. Adding 4.5 wt.% TiB₂ particles effectively optimizes α-Al grains in the 7075 aluminum alloy. By combining in situ reinforcing particles with the self-stirring effect of a serpentuator, rheocasting of the 7075 aluminum alloy was achieved in a simple and economical way. The average grain size of the specimen after rheocasting and heat treatment was smaller than 33 μm, and the shape factors were greater than 0.85. The wear resistance of the 4.5 wt.% TiB₂/7075 aluminum matrix composite that was prepared via rheocasting and gravity casting was tested with loads of 30, 60, 90, and 120 N at a friction speed of 0.15 m/s for a duration of 30 min. Because of the optimized microstructure and increased hardness, the wear resistance of the 4.5 wt.% TiB₂/7075 aluminum matrix composite was significantly better than that of the 7075 aluminum alloy, and the wear resistance of the rheocast TiB₂/7075 aluminum matrix composite was better than that of the gravity cast one.

In this study TC4/TC17 titanium alloy dissimilar joints were obtained via vacuum electron beam welding. The compressive behavior of base metals and joint at different strain levels was studied, along with microstructural and fracture surface observations. The true stress–strain curves of base metals and joint at different strains demonstrated smooth and continuous plastic deformation characteristics. The compressive yield strength of the joint (1065 MPa) was basically equivalent to that of TC17 alloy (1196 MPa), which was significantly higher than that of TC4 alloy (920 MPa) for the failed samples. However, the compressive fracture strain of the joint was lower than that of base metals. Comparison of the microstructures of base metals and joint deformed at different strains, it revealed that the equiaxed α phase in TC4 alloy mainly underwent the deformation, while the TC17 alloy mainly relied on the rotation of lamellar grains to resist the deformation. In the dissimilar joint with a large microstructural gradient, the compressive deformation of several zones, including the weld zone, far heat-affected zone and the base metal, was also related to the rotation of finer grains.