A first computer method has been proposed for the simulation of the local atomic displacement in alloys. Employing a Monte Carlo method the simulation has been carried out so that the local displacement parameters determined experimentally from diffuse-scattering measurements fit the simulationed ones. A whole feature of atomic fluctuations can be spacified by combining this method with Gehlen-Cohen method for the chemical short-range order in alloys.
This method has been applied to the structural problem of the G.P.zones in Al-Cu alloys. There are distinctive atomic displacements inside and outside the zone. In particular, it is interesting to note that the modulated displacement-waves spread over a relatively wide region surrouding the G.P.zone.