The effect of inert particles on grain structure development from alloy melt during laser rapid solidification has been investigated. It is found that the presence of Al₂O₃ particles may disrupt the usual epitaxial grain structure evolution of an aluminium 7075 alloy when processed by laser surface remelting. This result, in addition to observations of crystal termination at the particles and grain refinement in particle dense regions, indicates that a mechanism of particle restricted grain growth operates.

Ti and V were bonded together and subjected to high-temperature treatment at 1000 or 1100 °C for 16 h to study the microstructural evolution and interfacial behavior of Ti–V diffusion interfaces. The samples were prepared by electro-polishing and analyzed using scanning electron microscopy, electron probe microanalysis, electron back-scattered diffraction, and nano-indentation. The results indicated that Ti–V diffusion bonding interfaces comprises a martensite Ti zone, a body-center-cubic Ti (β-Ti) zone, and a V-based alloy zone. They are divided by two composition interfaces with V contents of ~13.5% and ~46%. The original interface between the pure Ti and the V alloy substrate falls within the β-Ti zone. The observation of acicular-martensite rather than lath-martensite is due to the distortion caused by the β-to-α phase transformation in the adjacent pure Ti. The recrystallization of β-Ti is distributed along the interface direction. The hardness varies across the Ti–V interface bonding zones with the maximum value of 7.9 GPa.

This paper applies bullet to induce shock wave and detects the adhesion behavior of multiple interfaces in typical thermal barrier coating system. Post-shock metallography examination is carried out to show the real characteristic of interface delamination. A finite element-based acoustic wave mechanics simulation is conducted to calculate the stress history. It is found that delamination can occur in every interface, depending on bullet velocity and stress feature. An interesting phenomenon of the failure at multiple interfaces during a single shot needs to be paid more attention in the future.

The microenvironment dominated by the electrode approaching velocity can be defined as the micro-gap ESD model. Micro-gap ESD is a time-domain continuous process, and the electrode approach velocity critically influences the characteristic discharge parameters. Based on two sub-processes, field electron emission and Townsend gas discharge, the experimental characteristic parameters are analyzed in time frequency. Wavelet neural network algorithm is also used to analyze and predict the discharge results. Remarkable variation appeared in discharge parameters of discharge current peak values, current derivative peak values, and arc length due to electrode approach velocity change in experimental measurement results of micro-gap electrostatic discharge. The higher the velocity, the larger the variation of discharge parameters. Threshold phenomenon emerged for discharge parameters variation with charge voltage due to electrode moving to the target at various velocities. For micro-gap ranging in 80–300 micrometers, electrode moving velocity enhanced the sub-process of electron surface emission. The approaching velocity is an important input index, and the wavelet neural network algorithm is used to analyze and predict the output results. The characteristics measured in the real experiment were compared with the prediction parameters from the wavelet neural network calculation result. According to the prediction data, a discussion was conducted on correctness accuracy and the discharge process trend analysis. Nonlinearity and discreteness are the main characteristics of discharge parameters.