Formation of Voids in Pure Aluminum Quenched in Hydrogen Gas

Abstract

Pure aluminum foil, nominally 99.999% pure and 50 µm thick, was heated at temperatures between 400°C and 650°C in hydrogen gas by passing direct current and then quenched in a liquid at temperatures between -10°C and 30°C. The number density of voids was examined by electron microscopy. At a constant quenching temperature, the number density was found to be constant for the variation of liquid temperature. In hydrogen at normal pressure, the concentration of voids increased as C void = A ×exp (- E void / k T Q ) with an increase in the quenching temperature T Q . A was determined to be 0.0011 and E void =0.86 eV. The number density of voids was found to be proportional to the square root of the partial pressure of hydrogen in a gas. These results indicate that a void is nucleated at the site of a single hydrogen atom dissolved in pure aluminum at high temperature, and that the concentration of voids corresponds to that of hydrogen dissolved in solid solution in pure aluminum.