On the solid solution softening in Fe-2.86at%Ni and Fe-2.94at%Si

Abstract

A consistent theory for the solid solution softening has not yet been established. An important question is whether or not the solid solution softening results from the same cause for all binary alloys. Arsenault (10) concluded that the solid solution softening in TaNb and TaW can be accounted for by a change in the Peierls stress due to a change in the modulus of the alloy. In the case of FeNi and FeSi, the changes in the moduli are too small to account for the observed large decrease in activation enthalpy. However, if the change in shear modulus, lattice constant and critical kink length are taken into consideration, decrease in activation enthalpy seems to be fairly well accounted for on the basis of the Peierls mechanism. Solid solution softening in FeNi may be interpreted in terms of electron configuration or cross slip. This interpretation can not, however, be applied to FeSi. Therefore, it is quite dangerous to derive the general conclusion on the cause of solid solution softening from the information of one alloy alone. The comparison between FeNi and FeSi is a good example to show it.