Question 13.13.2: The molar Gibbs free energy of mixing of Al2O3 and MgO at 10...

Introduction to the Thermodynamics of Materials [ EXP-7693]

The molar Gibbs free energy of mixing of $Al_2O_3$ and MgO at 1073 K is shown in Figure 13.17. Delineate the phase fields as the composition varies from

$X_{Al_2O_3}=0$ to $X_{Al_2O_3}=1$ .

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$X_{Al_2O_3}=0$ only MgO

$0\lt X_{Al_2O_3}\lt 0.5$ MgO and $MgAl_2O_4$

$0.5\lt X_{Al_2O_3}\lt 1$ $MgAl_2O_4$ and $Al_2O_3$

$X_{Al_2O_3}=1$ only $Al_2O_3$

Note : The diagram in Figure 13.17 is only approximate. There must be some solubility (however small) of each of the components in each other as well as in the spinel phase.

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