Ternary atom location in L12-structured intermetallic phases: Al62.5+XTi25−Y(Fe, Ni, or Cu)12.5–Z using ALCHEMI

Abstract

The site occupancy of ternary atoms in three L1₂-structured intermetallic phases, Al_62.5+XTi_25−Y(Fe, Ni, or Cu)_12.5–Z found in three laser processed intermetallic systems was studied by the axial ALCHEMI (Atom Location by Channeling Enhanced Microanalysis). The ternary atoms in all three intermetallic phases were found preferentially to occupy the Al sublattices, although slight differences in occupancy among them were detected. A simple extrapolation method of calculating delocalization correction factors for various characteristic x-ray emissions was described, which was proved to be practically useful in ALCHEMI analyses. In order to compare the axial ALCHEMI analysis with the planar ALCHEMI in an experimental perspective, the planar ALCHEMI analysis was also carried out on the phase alloyed with Cu, which showed results in broad agreement with those of the axial ALCHEMI analysis on the same phase. Nevertheless, owing to much weaker channeling effects the planar ALCHEMI analysis gave apparently worse statistics in its results. In the end, various sources of errors in the ALCHEMI analyses at the present stage are discussed.