Molecular dynamics study on formation and crystallization of Ti–Al amorphous alloys

Formation of the amorphous phase and its relaxation and crystallization processes in the Ti–Al binary system are investigated by using molecular dynamics techniques. For various Al concentrations ranging from 0.0 to 1.0, amorphous alloys are prepared by quenching from liquid state. By varying the cooling rates, we can obtain the critical cooling rate to get the amorphous state in each composition. The geometrical analysis shows that a structural inhomogeneity on nanometer scale exists in the amorphous state, which mainly consists of two regions. One is dominated by the icosahedral clusters and the other is filled with approximate crystalline packing. The excess of low frequency vibration modes called the boson peak is observed in the amorphous states, which is getting weaker during the annealing process and completely vanishes after crystallization.