In the present study, the microstructure and solution treatment response of Al-Zn-Mg alloys bars by thixo-extrusion was investigated. The alloy bars were solution treated at 400, 430, 460 and $490^{\circ}C$ for various times. In order to examine the microstructures and phase analysis of the samples after solution treatment, it was performed by optical and scanning electron microscopy. And, Vickers hardness and electrical conductivity was measured on the solution treated samples for each condition to investigate the solution treatment response of extruded bars during solution treatment. The results show that the optimum solution heat treatment conditions of thixo-extruded Al-Zn-Mg alloy for minimization of the grain growth and degradation promotion of the second phase is a temperature of $460^{\circ}C$ and holding time of 0.5 to 2 h.

Separation and recovery of valuable metals such as zinc, nickel or tin from copper alloy dross has recently attracted from the viewpoints of environmental protection and resource recycling. In this report, preliminary study on concentration and separation of tin from copper alloy dross using selective dissolution method was performed. The tin in the copper alloy dross did not dissolve in the nitric acid solution which could allow the concentration and separation of the tin from the copper alloy dross. Precipitation of tin as $H_2SnO_3$ (metastannic acid) occurred in the solution and transformed to tin dioxide ($SnO_2$) after drying process. The dried sample was heat-treated at low temperature and its phase characteristics, surface morphology and chemical composition were investigated.

The effects of thickness and surface grinding condition on the fracture strength of Si wafer with a thickness under $100{\mu}m$ were investigated. Fracture strength was measured by ball breaker test for about 330 dies (size: $4mm{\times}4mm$) per each wafer. For statistical analysis of the fracture strength, scale factor was determined from Weibull plot. Ball breaker fracture strength was observed to increase with decreasing thickness of silicon die. For the silicon dies of different surface conditions, ball breaker fracture strength was high in the order of polished, ground (#4800), and ground (#320 grit) specimen. Probabilistic fracture strength (i.e., scale factor) increased with decreasing surface roughness of silicon die.

Influence of solution treatment (T4) and peak-aging (T6) on damping capacity was investigated in permanent-mold cast Mg-3%Nd alloy. In as-cast state, the microstructure was characterized by eutectic $Mg_{12}Nd$ intermetallic phase network in the intergranular region. T4 treatment resulted in a dissolution of the eutectic particles, but small amount of the particles still remained in the microstructure. After T6 treatment, nano-sized ${\beta}^{\prime}(Mg_{12}Nd)$ particles were precipitated within the matrix. T4 microstructure showed higher damping capacity than as-cast and T6 ones. In view of the microstructural features, this may well be associated with the dissolution of second-phase particles which play a role in pinning the dislocations acting as a damping source.