Results are presented from ultrasound studies of the melting and crystallization of eutectic In–Ga alloys with indium contents of 6, 9, and 15 at % in porous glasses with a pore size of 7 nm. The effect the confined geometry and composition of the alloy have on the formation of different crystalline phases of gallium and the ranges of melting temperatures is revealed. New high-temperature phases of gallium are found in an alloy with an indium content of 9 at %.