Effect of topologically close-packed clusters on the pair distribution function of amorphous Zr under different pressures

Abstract

With the development of high-pressure technology, pressure as a thermodynamic parameter is an important variable to control and influence the glass transition of metal melt. Therefore, in order to explore the influence of pressure on the glass transition of zirconium (Zr) melt under rapid solidification, the molecular dynamics simulation method has been adopted to obtain Zr metallic glass (MGs) by rapid solidification at the cooling rate of 1.0 × 1011 K/s under five different pressures. The results indicate that the glass transition temperature (Tg) and the topologically close-packed (TCP) clusters have increased with the increasing pressure, resulting in the reduction of configurational entropy. The second peak of the pair distribution function (g(r)) gradually changes from the left lower than the right to the left higher than the right. A13[1/S444 10/S555 2/S666], Z12[12/S555], and Z14[12/S555 2/S666] clusters increase significantly with the increasing pressure, which is the reason for the second peak splitting of the g(r) curve. At 57.5 GPa (P5), Z12 and Z14 which account for 16.8% are concentrated in space and form large nanoclusters with a layered distribution. In the layered structure, Z12 and Z12 are connected by edge-sharing (ES), but Z12 and Z14 are connected by intercross-sharing (IS). It is confirmed that the second peak splitting of the g(r) curve is mainly caused by Z12, Z14, and both connecting. The distance from the peripheral atom to the central atom corresponds to R2/R1 = 1.56, R3/R1 = 2, and R4/R1 = 2.46 of the g(r) curve, and R1–4 represents different radial distances respectively. These results provide theoretical guidance for understanding the influence of pressure on the microstructure of MGs.