Glass formation and icosahedral medium-range order in liquid Ti–Al alloys

In this paper, molecular dynamics simulations are applied to explain the glass formation processes of Ti–Al alloys in structural perspective and to reveal the microstructural evolution of Ti–Al alloys during rapid solidifications in icosahedral medium-range order. The icosahedral medium-range order structural evolutions are described in detail by icosahedral connectivity parameter and coordination number during the rapid solidifications. The results reveal that the icosahedral medium-range order is an appropriate structural unit, which aptly describes glass formation processes of liquid and amorphous Ti–Al alloys in structural aspect. Furthermore, hexagonal connected icosahedral clusters, which link via volume-sharing, have good structural stability and configural continuity, and act as the junction closely connects nearby extended icosahedral clusters. At the same time, the number of the hexagonal formation after the rapid solidification could properly reflect the glass forming abilities of the Ti–Al alloys with different compositions.