Isothermal grain growth of reactive spray formed 7075 alloys in semi-solid state

The grain growth behavior in reactive spray formed 7075+2.91vol%TiC Al alloy was studied and compared with that of spray formed 7075 Al alloy at semi-solid state. The effects of in-situ TiC particles on the microstructure of spray formed 7075 Al alloy were also investigated. The specimens were heat-treated isothermally at various temperatures between the solidus and liquidus of 7075 Al alloy for times in the range of 10-60 min, then quenched in water. The microstructure of reheated specimens was characterized using scanning electron microscopy and optical microscopy. The grain size was measured using a mean linear intercept method.Results show that the in-situ TiC particles can effectively retard grain growth and refine the grain at a limited size. The grain growth exponent in Arrhenius equation increases from 2 to 3, which indicates that the in-situ TiC particles have the significant pinning effect on grain coarsening in the semi-solid state.