Stainless steels are important technologically for a wide range of applications. Though they are attractive for their environmental stability, austenitic versions of these steels are not generally known for their very high strength. We have rapid-solidification-processed many stainless steels by gas atomization and achieved strength improvements of over 50% relative to conventionally-processed stainless steels with concomitant improvement in corrosion and oxidation behavior. These strength improvements are most pronounced when elevated concentrations of oxygen and vanadium are present in the metal and we need to know how these elements affect precipitation in the alloy.
The specimen material (FCC Fe-16%Ni-9%Cr-0.5%Mn-0.2%V-0.0137%N-0.008%O by weight) was prepared by gas atomization and hot extrusion followed by precipitation aging as described elsewhere. We observed the structure in TEM and found 20 nm precipitates on dislocations, Fig. 1a. We did not observe smaller precipitates in the grain interiors using diffraction contrast bright field imaging, however, with weak-beam dark field imaging, Moiré fringe contrast is observed throughout the material, Fig. 1b.