The metals $Al$ and $Ca$ form the compounds $Al4Ca$ and $Al2Ca.$ The solids $Al,Ca,Al4Ca,$ and $Al2Ca$ essentially are immiscible in each other but are completely miscible as liquids. Maximum Ca solubility in $Al$ is about $2\%$ and occurs at $616C.$ Al melts congruenily at $1079C$ and gives a simple eutectic with Ca at $545$ C$.$ Compound Al$4$Ca decomposes at $700C$ to give $Al2Ca$ and a melt, the periteotic lying at $10$mol$\%.$ A monotectic exists at $616$ C$.$ At approximately $450C$ a transition occurs between $-$Ca and $-$Ca$.$