In the Fe$-$C system Fe$3$C is only a metastable phase, while graph$-$ ite is the most stable carbon$-$rich phase. By drawing schematic free energy$-$composition diagrams show how the Fe$-$graphite phase diagram compares to the Fe$-$Fe$3$C phase diagram from $0$ to $2$ wt$\%$ Fe$.$ Check your answer with the published phase diagram in the Metals Handbook for example.