Density Measurement and Atomic Structure Simulation of Metastable Liquid Ti-Ni Alloys

The temperature dependence of the densities of liquid Ti-Ni alloys was investigated by the electrostatic levitation technique and molecular dynamics simulation. The average cooling rate by natural radiation decreases with a reduction in Ti content and reaches its minimum at Ti₅₅Ni₄₅ alloy. The Ti-Ni alloy system exhibits a negative excess volume and it becomes smaller with the increase in undercooling. This indicates that the interactions among atoms are enhanced with the decrease in temperature. The pair correlation functions and static structure factors are obtained from the molecular dynamics results. It is found that the packing of the Ni atoms does not occur through replacement of the Ti atoms with the addition of Ni atoms. In addition, the clusters are abundant in liquid Ti-Ni alloys, and a tetragonal bipyramid atomic configuration of may exist. It is found that the Ni-Ni bonds transform to Ti-Ni bonds with the increase in Ni content.