Glass-forming ability determined by ann-body potential in a highly immiscible Cu-W system through molecular dynamics simulations

Abstract

With an important aid from ab initio calculations, an n-body potential is constructed under the embedded atom method for a highly immiscible Cu-W system characterized by a positive heat of formation of +33 kJ/mol. The obtained potential is capable of reproducing some realistic physical properties, such as cohesive energies and lattice constants, etc., of Cu and W, as well as two nonequilibrium ${\mathrm{Cu}}_{3}\mathrm{W}$ and CuW compounds. Applying the potential, molecular dynamics simulations using solid solution models are conducted to calculate the critical solid solubility, at which a metallic glass transition takes place, thus determining the glass-forming range of the Cu-W system to be from 20 to 65 at. % of W, which is in good agreement with the experimental results. Interestingly, an abnormally large volume expansion in association with the transition is found to be within 6.9--13.1% in the Cu-W system and it is much greater than the typical value of 1--2% frequently observed in the systems with negative heats of formation.