The phase equilibrium diagram of the system CaO-Al2O3-CaF2

The phase equilibria of the system CaO-Al₂O₃-CaF₂ have been studied by quenching in sealed platinum capsules followed by microscopic and X-ray examination of quenched products. The established phase diagram contains five ternary eutectics, two ternary peritectics and two invariant points of four-phase monotectic transformations. The system Al₂O₃-CaF₂ has been established to be the stable diagonal of the reversible reciprocal system Al₂O₃ + 3CaF₂ = 3CaO + 2AlF₃. In the high-fluoride region a wide zone of liquid immiscibility has been found. The system also shows such rarely noticed but theoretically possible phenomena as the transformation of peritecticals into eutecticals and occurrence of three different primary fields under single continuous zone of liquid immiscibility.