Neutron Scattering Study of Dynamical Scaling Properties in the Relaxation of Short-Range Clustering and Decomposition of Cuni(Fe) Alloys

A neutron scattering study on a number of CuNi(Fe)-alloys has been undertaken in order to test some recent theories on the relaxation of short-range clustering and decomposition with special emphasis on scaling properties. The structure functions $${\rm{S}}(\bar \kappa ,{\rm{t}})$$ , have been determined for samples, which had undergone a large number of different heat treatments resulting in different thermodynamic states. The analysis of the structure functions during relaxation of short-range clustering showed that even in these cases the assumption of small concentration fluctuations made in Cook’s theory for spinodal decomposition is not always valid. Moreover, for the relaxation of short-range clustering and the very early stages of decomposition no scaling behaviour could be found. However, for some particular cases close to the spinodal, after a certain transient time, the structure function could be transformed into a time-independent function. The main conclusion is that the kinetics of relaxation above as well as within the miscibility gap show similar characteristics, but there is no universal description applicable to all different regimes.