11. Al2O3 and Cr2O3 display unlimited (complete) solid solubility.
a) Draw a hypothetical binary phase diagram for Al2O3-Cr2O3 system, and label the curves, regions, etc.
(Melting temperatures of Al2O3 and Cr2O3 are 2045°C and 2275°C, respectively).
b) Which requirements should be satisfied to obtain a complete solid solubility?