Peculiarities of structural state of aged Fe-30%Ni-4%Al alloy

Electron microscopy and Moessbauer-graphy were employed to study the sequence of structural states in the process of ageing of a Fe-30.2% by weight Ni-4.2% by weight Al alloy. It was shown that the ageing of the Fe-Ni-Al alloy gives rise to a structure, which can be described as a superposition of concentration waves with wave vectors oriented along directions of the (110) type. Such a distribution of concentrations produces a field of deformations, which can be represented as superpositions of transversal waves of atom displacements with polarization vectors oriented along (110). A surface relaxation of elastic stresses determines to a substantial degree the deformation contrast as compared to the above concentration distribution