This study introduces a new apparatus for quantitative assessment of hot tearing tendency in casting alloys. In this method, molten metal is cast in a T-shaped mold cavity. Each arm of the T-shaped casting is hooked onto a rigid flask which restrains its free contraction during solidification. One of the hooks connects to a load cell which enables the real-time measurement of the contraction load during the solidification process as well as the load-time curve of each experiment. Temperature-time curves are also plotted using K-type thermocouples placed in the casting hot spot and connected to a data-acquisition system. Through the use of this set up, it is possible to estimate the solid fraction at which hot tearing occurs. Experiments were conducted with Al-9 %Si alloy to investigate the accuracy of the apparatus and modify its operation. The influence of the mold thermal gradient on the load-time curve and the hot tearing severity were investigated. Microscopic study of the observed hot tear regions was also performed to characterize the hot tearing characteristics.

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A metal–matrix composite was developed by eco-friendly accumulative roll bonding process and agricultural wastes. Amorphous silica particles were obtained by heating rice husk at 600℃ and then ball milling. Amorphous silica particles as a reinforcement were embedded in a matrix of aluminum 1100. Composites with various amounts (1%, 2%, 3%, 4%, 5%, 6%, and 7%, mass fraction) of rice husk ash particles were developed. The produced aluminum–rice husk ash composites were evaluated for structural changes and mechanical properties. The scanning electron micrographs showed a uniform distribution of rice husk ash particles and were bonded well with the aluminum matrix after 10 cycles. By increasing the rice husk ash content, the composite strength increases first and then becomes constant because of the inappropriate connection of aluminum sheets. Increasing the rice husk ash content of the composite causes the change from the ductile to a relatively brittle type of fracture.