Electron Microscopic Study of Deformation Behavior of Iron-40 wt% Chromium Alloy Aged at 470°C

Abstract

The deformation behavior of an aged iron-chromium alloy at 470°C has been investigated by means of measurements of electrical resistivity and electron microscopic observations, in order to make clear the embrittlement of the iron-chromium alloy aged at 475°C.
The electrical resistivity of the aged iron-40 wt% chromium alloy which were measured at the liquid nitrogen temperature increased with increasing aging time.
The deformation substructure of the slightly deformed brittle specimens remarkably differs from the slightly deformed ductile specimens, in the former deformation twins were directly observed by transmission electron microscopy and dislocations were streight although by no means smooth. In the latter dislocations showed a rather irregular form and irregular tangles were observed scatteringly.
The specimens aged for a long time at 470°C fractured generally by cleavage with a few isolated regions of intergranular fracture and many twin traces were observed at the fracture surface.
Deformation twins observed in the aged and slightly deformed specimens seem to be closely related to the embrittlement of the aged iron-chromium alloy.