In this paper, the microstructure and properties of a Ti/Mg alloy clad plate manufactured by explosive welding were studied. The bonding interface was inspected by ultrasonic examination (US). The microstructure and the composition of the clad were characterized by OM and SEM. Properties were inspected by tensile test, shearing test, microhardness test and electrochemical corrosion. The results showed that the bonding interface of the clad plate was made up of straight areas and wavy areas. In straight areas, element diffusion occurred across the bonding interface. Additionally, in wavy areas, a melting zone occurred in the Mg alloy layer near to the bonding interface. Lots of light particles embedded on the melting zone. Tensile test results were comparable with the Ti sheet and the ultimate tensile strength of the clad plate demonstrated an 18% increase. The shearing strength of the clad plate was about 68–87 MPa. The microhardness of the clad plate was higher than that of the original sheets from the interface to 300 μm away. At over 300 μm, the microhardness of the clad plate decreased and approached the original sheets. Compared with the straight area, the hardness of the Mg alloy layer in the wavy area close to the interface increased by 12%. Corrosion results showed that the corrosion potential (E_corr) absolute value of the clad plate increased by 24%, and the corrosion current density (i_corr) value was 4 orders of magnitude lower, compared with the Mg alloy sheet. It was clear that the corrosion resistance of the clad plate was higher than that of the Mg alloy sheet. Cladding Mg alloy and Ti by explosive welding would improve the industrial applications of magnesium materials.

Nickel-based single crystal superalloy is the most important material for blade preparation. However, some solidification defects inevitably occur during the process of preparing single-crystal blades through directional solidification. In this study, in order to study the origin of misorientation defects during solidification, a model with rejoined platforms was designed according to the geometry of single-crystal guide vanes. Electron Back-Scattering Diffraction (EBSD) was used to quantify the orientation deviation of the dendrites and identify the solidification defects in the rejoined platforms. The results showed that stray grain defects appeared in the platforms and their misorientation changed gradually, not abruptly. Combined with the simulation results, it was proposed that the stray grains formed as the result of the dendrites fragment, which was induced by solute enrichment in the mushy zone during solidification. Meanwhile, it was accompanied by a obvious dendritic deformation, which was caused by solidification shrinkage stress. This suggested that the fragmentation was induced by multiple factors, among which, the concave interface shape provided favorable conditions for solute enrichment, and the dynamic variability in the local thermal gradient and fluctuations of the solidification rate might play catalytic roles.