General formulation for ALCHEMI

This paper is concerned with equations used in channelling-enhanced microanalysis for the site occupancy determination of substitutional alloying elements (called atom location by channelling-enhanced miroanalysis: ALCHEMI). An equation is derived which can be of a general form encompassing various premises on the antistite occupation of host elements involved in the equations proposed earlier. It is shown that the general equation can be expressed by a unique function of measurable values and known parameters so that no iterative calculation is required for the site occupancy determination. It is also shown that the general equation permits the site occupancy determination of any element in multicomponent systems and at beam incidence parallel to more than two types of planes or columns. An application of the equation is presented using an Ni3Al-based Ni75Al21Ta4 alloy with the L12-type crystal structure.