Effect of Solute Addition on the Formation of Vacancy Condensation Pits

摘要

The effect of alloying elements in aluminum on the phenomenon of pit formation has been studied. It is suggested that alloying elements will affect; (1) the vacancy supersaturation, (2) the migration energy of the vacancies; and (3) the nature of the oxide‐metal interface. It was found that there are four main types of effects of solute addition on the formation of pits. (a) Pits are not observed (Al1.05% Mg alloy). (b) Pits appear with a larger ΔT than for pure aluminum, and ΔT decreases with increasing holding temperature (Al1.07% Zn alloy and Al0.57% Cu alloy). (c) Pits appear with a larger ΔT than that for pure aluminum and ΔT does not follow any regular trend (Al0.0045% Sn alloy). (d) Pits are not observed, but a rippled structure appears on the surface of the specimen (Al0.96% Sn alloy).