 Solution

ID: past-exam-of-the-materials-science-course-of-the-university-of-cambridge/2016/paper-1/4/c/i/solution

Apply the lever rule on the

77 9^{\circ} C

solid tie line. All compositions are copper mass percentages:

w_{α} = \frac{92 - 28}{92 - 9} = \frac{64}{83} = 0.7711, w_{β} = \frac{28 - 9}{92 - 9} = \frac{19}{83} = 0.2289.

Thus the equilibrium material is 77.1% $α$ and 22.9% $β$ by mass just below the eutectic temperature. These are phase fractions; converting them to volume fractions would require densities.

 New to topics? Read the docs here!