5. An iron-carbon alloy contains 25 wt% primary austenite at 1145C. a) Calculate the composition of the alloy, in wt% C. (2 Marks) b) Calculate the mass fraction of eutectic austenite. (3 Marks) The alloy is now cooled to 725C and allowed to reach equilibrium conditions. c) Calculate the mass fraction of eutectoid cementite. (3 Marks) Composition (at% C) 10 15 20 25 1600 1538C 1493C L 1400 2500 1394C Y+L 1200 1147C 2.14 4.30 7. Austenite 2000 Temperature (C) 1000 Temperature (F) 912C y + Fezc 800 1500 727C 0.76 0.022 600 a, Ferrite a + Fezc Cementite (Fe3C) 1000 400 0 (Fe) 2 6 6.70 3 4 Composition (wt% C) Note, round all your answers to three decimal places