**Unformatted text preview: **It first becomes necessary to compute mass fractions using the lever rule. From the iron-carbon phase diagram (Figure 12.5), the tie-line in the α and graphite phase field extends from essentially 0 wt% C to 100 wt% C. Thus, for a 3.5 wt% C cast iron W α = C Gr- C o C Gr- C α = 100 - 3.5 100 - 0 = 0.965 W Gr = C o- C α C Gr- C α = 3.5 - 0 100 - 0 = 0.035 Conversion from weight fraction to volume fraction of graphite is possible using Equation (9.6a) as V Gr = W Gr ρ Gr W α ρ α + W Gr ρ Gr = 0.035 2.3 g/cm 3 0.965 7.9 g/cm 3 + 0.035 2.3 g/cm 3 = 0.111 or 11.1 vol%...

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