Two metals, A and B, form a substitutional alloy with the binary phase diagram shown here. Determine the composition and relative amounts of the two phases present at 50% composition and 1500 °C.

a) The A-rich bcc phase is 80% A and 20% B; the B-rich fcc phase is 37% A and 63% B; the mixture contains more of the A-rich fcc phase.

b) The A-rich bcc phase is 20% A and 80% B; the B-rich fcc phase is 63% A and 37% B; the mixture contains more of the B-rich fcc phase.

c) The A-rich bcc phase is 50% A and 50% B; the B-rich fcc phase is 50% A and 50% B; the mixture contains equal amounts of both phases.

d) The A-rich bcc phase is 80% A and 20% B; the B-rich fcc phase is 37% A and 63% B; the mixture contains more of the B-rich fcc phase.

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Temperature (°C) 2000- 1750 1500- 1250 1000 A alloy (bcc) 0 Pure A 25 Liquid Two-phase region 50 Mole percent B 75 B alloy (fcc) 100 Pure B