investigating the effect of al addition to the zr50cu50 binary alloy on the structure and atomic short-range order using molecular dynamics simulation

Since the first discovery of amorphous materials by rapid solidification in the 1960s, there has been continuously growing interest in metallic glasses, particularly the cu-zr-based bulk metallic glasses (bmgs), and other non-equilibrium materials. in addition to the scientific importance of mgs for glass and liquid-state physics, bmgs have been paid great attention in materials science and engineering, due to having unique properties such as ductility, high strength, catalytic ability, high corrosion resistance, and soft magnetism. in this research, the short-range ordering in (zr0.5cu0.5)100-xalx (x=0,4,8) metallic glass alloys was investigated utilizing the classical molecular dynamics simulation method. different techniques, like the voronoi tessellation, the pair distribution function (pdf), the partial pair distribution function (ppdf), and mean squared displacement (msd) were adopted to investigate the effect of al addition on the structure and local ordering of the binary zr-cu alloy. it was found that all the samples in the range of chemical composition studied formed the glassy structure after quenching to 300k. it was observed that by increasing the al content, the glass transition temperature (tg) increases. the deviation of the glass transition temperature trend from the gfa trend revealed the necessity of employing the 3d structural analysis methods. thus, to identify the most important structures stabilizing the glassy state and hindering the crystallization, the evolution of local structures was evaluated. our results showed that cu-<0,2,8,2>, cu-<0,2,8,1>, cu-<0,0,12,0>, and al-<0,0,12,0> possess the most abundant frequency and variations in the supercooled liquid region. it was found that cu- and al-centered full icosahedra possess the most frequency accompanied by the most changes during the glass transition process in the supercooled liquid region temperature and, the cu-fi and al-fi seem to be the most geometrically stable structures in the composition range compared to the other local structures. according to the potential energy per atom criterion, it was observed that the cu-fi and al-fi structures have the highest stability and the lowest distortion compared to the other local ordering structures. therefore, these two structures possess the most effect on the gfa enhancement. the relative-msd results revealed that the cu-fi structure compared to the al-fi and other local structures has higher stability and lower mobility. based on ppdf analyses, the lengths of al-zr and al-cu bond pairs are shortened by 1.39% and 6.96%, respectively. this reveals that the distribution of atoms in the first-order atomic neighboring is not random, and there is a chemical short-range order (csro) around the system elements. hence, in addition to the topological short-range order (tsro), the chemical short-range order (csro) should be considered as a structural stabilizer in local-ordering structures, and the csro affects the gfa as well.