The β′→ζ Transformation in Equiatomic AgZn Alloy

Abstract

An analysis was made of the X-ray diffraction intensity distribution in a series of single crystal patterns of an equiatomic AgZn alloy recorded at the initial stage of the phase transformation from β′ (B2-type ordered structure) to ζ (trigonal structure). It was shown that the displacements of atoms and the partial disordering, the two atomistic mechanisms involved in the transformation, proceed simultaneously. The ζ phase nuclei grow gradually in the β′ phase matrix with a definite orientation relationship. Two types of the nuclei form; one with a structure similar to the structure proposed for the ζ phase by Edmunds and Qurashi (ζ phase-type structure) and the other with a structure obtained by reversing the direction of the displacements of some of the atoms in the ζ phase-type structure (anti-ζ phase-type structure).