Spherical monocrystals for X-ray work obtained by plasma remelting of alloy powder

Spherical crystals of alloy phases too hard and brittle for grinding can be obtained by partial remelting and solidification of a powder sample. The alloy powder is blown through an argon-plasma jet melting the surface material of individual fragments, which solidify again as nearly perfect spheres. The yield is a mixture of different materials in which it is possible, however, after heat treatment to find good single crystals of the original composition. Spherical single crystals of Cu₉Al₄ have been produced by this method and used for a high-precision X-ray investigation described elsewhere.