Austenite-ferrite interface crystallography dependence of sigma phase precipitation using the five-parameter characterization approach

In the current study, the propensity of austenite-ferrite interface to sigma phase precipitation was investigated in a duplex stainless steel. The crystallographic characteristics of the interphase interfaces significantly affected the tendency to sigma phase precipitation. The lattice misorientation was found to be an insufficient criterion to fully define the interface character and ultimately the propensity of austenite-ferrite interface to sigma phase precipitation. The interphase interfaces with a rational orientation relationship, considering all five crystallographic parameters, generally exhibited the lowest sigma precipitation propensity. This could be attributed to the high sigma precipitation nucleation barrier energy and low diffusion rate at (semi-)coherent interphases.