A method casts a plurality of alloy parts in a mold (600; 700) having a plurality of part-forming cavities (601). The method comprises pouring a first alloy into the mold causing: the first alloy to branch into respective flows along respective first flowpaths (676, 684; 708) to the respective cavities; and a surface of the first alloy in the part-forming cavities to equilibrate. The method further comprises pouring a second alloy into the mold causing: the second alloy to branch into respective flows along respective second flowpaths (676, 680; 712) to the respective cavities.