Metastable alloy phase formation from undercooled steel and TiAl melts

Metastable materials produced from deeply undercooled melts can provide some interesting materials properties. This review surveys recent studies of rapid and/or undercooled solidification in FeNi or FeCrNi steels and TiAl alloys. The effects of compositions and processes on the formation of metastable phases are discussed in terms of thermodynamic stability and the kinetics of nucleation and growth. In addition, a new approach by nucleation control is proposed to produce metastable materials.