Role of processing parameters on microstructural evolution of spray formed Al–2Mg alloy and Al–2Mg–TiO2 composite

Effects of processing parameters such as flight length and rotation speed of the substrate on microstructural evolution of spray formed Al–2Mg alloy and Al–2Mg–TiO2 composite are studied. Microstructural observations reveal equiaxed grains in both Al–2Mg alloy and Al–2Mg–TiO2 composite. The average grain size values of Al–2Mg alloy at the bottom, centre and top of the preform are 40, 75, and 30 μm, respectively. The variation in grain size is because cooling rates are different at different locations of the preform. Similar non-uniformity in grain size has also been observed in the Al–2Mg–TiO2 composite preform. The TiO2 particles are uniformly distributed in the Al–2Mg–TiO2 composite preform with good interfacial bonding. Processing parameters play important roles on porosity distribution in the spray formed preform. In this study, process variables, namely flight length and rotation speed of the substrate have been optimized. Results show that the optimum flight length and rotation speed of the substrate are 30 cm and 8 rotations per minute (rpm), respectively.