The Fe-C phase diagram is shown below. Temperature (C) 1600 1400 1200 1000- 800 1538C 600 912C 400 0 (Fe) Y -1493C 1394C Austenite 0.76 0.022 a, Ferrite 1 5 y+L 2 2.14 Composition (at% C) 15 10 1147C a + Fe3C L 4 3 Composition (wt% C) 4/30 y+ Fe C 727C 2 20 Cementite (Fe3C). 5 6 25 2500 2000 1500 1000 6.70 (a) How many invariant points exist in this phase diagram (b) Sketch the microstructure at point 1. (c) At the eutectic composition, the melt at 1250C is slowly cooled down point 2. Sketch their microstructures and explain. (d) In the question (d), calculate the weight portion of a-phase at point 2.