Molecular dynamics study of liquid metal infiltration during brazing

Molecular dynamics (MD) simulations are presented to investigate the rate of infiltration of liquid Cu through a channel in crystalline Ni. Two temperatures, T = 1750 K and 1500 K, are studied using two types of simulations: non-dissolutive (ND), where Ni atoms are held fixed, and dissolutive (D), where Ni atoms relax according to MD equations of motion. At T = 1500 K the penetration rate agrees well with theoretical models based on capillary forces, regardless of Ni dissolution behavior. At T = 1750 K data cannot be explained based solely on capillarity; however, this discrepancy is remedied by including an additional driving force for infiltration that is directly proportional to dissolution rate. A model for dissolution rate as a function of liquid composition and temperature is presented. For Ni dissolving into pure Cu(l) the dissolution rate exhibits Arrhenius temperature dependence and this is used to explain differences in infiltration behavior at the two temperatures studied.