Abstract

Spectroscopically pure Cu has a lattice parameter a25 = 3.61491 A (corrected for refraction), and a thermal expansion coefficient = 14.87 x 10-6DegreesC-1 between 15 and 55DegreesC. The measured density d25 is 8.9314 plus or minus 0.0002 g.cm-3 in agreement with the calculated value dx = 8.9316. In the solid solution region additions of In increase the lattice parameter of Cu according to ax = 3.6149 + 0.0091x up to x = 10.4 (x = atomic % In, balance Cu). The thermal expansion coefficients between 15 and 65DegreesC of the homogeneous alloys increase from 14.87 (pure Cu) to 17.2 x 10-6DegreesC-1 at the solid solubility limit (10.4 atomic % In, quenched from 650DegreesC). With the increase of In content the experimental densities become increasingly lower than the calculated ones because of void formation. Upon cold rolling the voids close and the differences disappear. The phase represents a substitutional solid solution without structural defects. Alloys quenched from the liquid state do not show any microporosity; the voids appear after homogenization at 800DegreesC. Micropore formation is explained by differential shrinkage of the various crystalline fractions formed during solidification, giving rise to internal stresses in the solid alloy. Relief of stresses results in vacancies or micropores, which coalesce into voids upon heat treatment.