Optical microphotographs of Al–7Si alloy (a) un-treated, (b) with grain refiner (1% of M13), (c) with modifier (0.02% Sr) and Al–7Si–2.5Cu alloy (d) un-treated, (e) with grain refiner (1% of M13), (f) with modifier (0.02% Sr) and (g) with grain refiner (1% of M13) and modifier (0.02% Sr).