Tensile tests for large gold, silver and copper crystals

Abstract

Large crystals of a number of metals have been made by Bridgman by slowly lowering a tube containing the metal through a furnace so that it cools from one end. By using a graphite tube Davey succeeded in making copper crystals by this method. He obtained crystals over six inches long and up to nearly one inch in diameter. The present paper describes some tensile tests on gold, silver and copper crystals which have been made by this method. Rods of the metal were melted in graphite tubes 0.25 inch diameter and 10 inches long, tapered at, one end. These were slowly lowered by clockwork through a platinum-wound electric tube furnace, the middle portion of which was maintained at, 100°C. above the melting-point of the metal. Nitrogen was passed slowly through the tube to prevent oxidation. In some cases the whole rod (about eight inches long) consisted of one crystal. It does not seem to be essential that the graphite tube should be tapered, as it, was sometimes found that a crystal growing from the point stopped a short distance up tire rod, and that a new crystal beginning here occupied the whole cross-section of the rod for the length that remained.