The m phase layer on ion nitrided austenitic stainless steel (III): an epitaxial relationship between the m phase and the gamma parent phase and a review of structural identifications of this phase

As we previously confirmed, the m phase, forming as a single-phase layer up on ion nitriding of AISI 316L stainless steel under mild conditions, has a centered tetragonal structure with strong composition dependence of the axi al ratio, cia, and, as recently reported, a strong duplex {111} and {100} t exture normal to the surface with a surprisingly strong in-plane directiona l component. This texture is now demonstrated to be an extension of a corre sponding duplex texture of the austenitic gamma parent phase, with m growin g epitaxially on and into the gamma phase. Since there are some other inter pretations of the m phase structure in the literature, a comparative discus sion and additional data are given in Appendix A. (C) 1999 Elsevier Science S.A. All rights reserved.