High-temperature reactive wetting systems : Role of lattice constant

The high-temperature spreading dynamics of Al-Cu(l)/Ni(s) and Al-Ni(l)/Ni(s) wetting systems was studied using molecular dynamics simulations. Accompanied with spreading, a significant dissolution reaction was noted to take place for the two studied systems. The dissolution reaction involves both diffusion of solid atoms into the droplet and incorporation of liquid atoms into the substrate. No precursor film is generated during spreading, since its formation is suppressed by the dissolution reaction. The dissolution reaction induces an enhanced spreading rate, and spreading becomes faster when droplets contain less Cu or Ni atoms. The dissolution of solid atoms into the droplet is faster than that of liquid atoms into the substrate, so that the dissolution of the former is the dominant driving force for the spreading enhancement. The spreading of Al-Cu droplets correlates with that of Al-Ni droplets so long as the Cu concentration in Al-Cu droplets is equal to the Ni concentration in Al-Ni droplets, since both Cu and Ni atoms have the identical lattice constants.