73 The solidification path of as-cast Mg4Al1.5Sr is shown in Figure P7.3a and its micrograph in Figure P7.3b. The calculated solidification path is aonqe. The amount of phase is too little to see in the microstructure. (a) Are the (Mg,Al)17Sr2 and (Mg,Al)4Sr phases in the microstructure consistent with the solidification path? (b) Compare the amounts of phases here with those in as-cast Mg4Al3Sr in Figure 7.28b and explain the differences. Figure P7.3 Mg-4Al-1.5Sr alloys: (a) solidification path (aonqe) shown on the liquidus projection of ternary Mg-Al-Sr phase diagram; (b) solidification microstructure. Source: From Soysal and Kou [29]