COSEGREGATION-INDUCED MORPHOLOGICAL INSTABILITIES OF (110)-ORIENTED AND (111)-ORIENTED SURFACES OF RANDOM MIXING BODY-CENTERED-CUBIC ALLOYS

Cosegregation-induced morphological instabilities of (110)- and (111)- oriented surfaces of random mixing body-centered-cubic alloys have bee n studied with Auger electron spectroscopy, low-energy electron diffra ction, and scanning electron microscopy. Surface cosegregation has bee n investigated on (110)and (111)-oriented Fe-15%Cr-N, Fe-3%V-C, Fe-3%V -N, and Fe-3%V-C, N single crystals. Cosegregation induces the facetin g of the bcc(lll) and (110) alloy surfaces. In all cases studied the f acet orientation is {100} allowing the epitaxial stabilization of the binary and ternary surface compounds and surface precipitates CrN, VC, VN, and V(C,N). The morphological instability of the bcc(110) surface is rationalized by a missing- and added-row reconstruction model whic h demonstrates the formation of {100} microfacets.