Abstract: The grain growth behavior of melt in-situ reaction spray deposited 7075+TiC (2.91%, voluminal fraction) alloy were studied, and the effect of in-situ TiC particles on the microstructure of spray-formed 7075 alloy was investigated. The sectioned specimens were heat-treated isothermally at various temperatures between the solidus and liquidus of 7075 alloy for times in the range of 10-60 min, then quenched in water. The microstructure of reheated specimens was characterized using SEM and the grain size was measured using a mean linear intercept method. It is shown that the in-situ TiC particles can effectively control grain size even at 600℃ after 60 min.