Order and phase separation in alloys

In an initially homogeneous alloy quenched from high temperature, local ord ering and/or phase Separation may occur on the way towards thermodynamic eq uilibrium at a lower temperature. Some of the related diffuse scattering ef fects, including those around the primary beam (small-angle scattering), ar e presented, and some recent results of X-ray and neutron scattering studie s of short-range order and decomposition in some alloys are discussed.