A2 An alloy composed of 80 atom % rhodium and 20 atom % rhenium is being slowly cooled from 3500 C during processing. Equilibrium is maintained at each temperature. Use to phase diagram below to answer the following: a. At what temperature does the first solid form and what is the composition of that solid? b. At what temperature does the last liquid solidify, and what is the composition of the last liquid? C. Which phases exist at 2000 C and what is their composition? Give the fraction of each phase. How many degrees of freedom are there is this equilibrium? d. Sketch the AGM-composition and activity-composition relationship for rhodium (Rh) at temperature indicated (~2250 C). Be sure to specify the compositions as accurately as possible. 3500 3188C 3000 Liquid a + liquid 2820 24 2500 B + liquid 2000 Temperature (C) 1983C a a + B 1500 B 1000 -88 1 500 IL 20 ! 90 Do 10 30 40 50 60 70 80 100 Rh Re Rhodium (atom %)