Effect of heterogeneous particle size on nanostructure evolution: A phase-field study

•A phase-field model is developed to study the effect of heterogeneous particle size.•Effect of heterogeneous particle size on microstructural evolution of nano-porous thin film is systemically explored.•Inverse Ostwald ripening is observed for nano-sized particles of unequal size.•In the nano-porous thin film, core-shell structure formation is observed in case of high surface diffusivity.