Characterization of multilayer diffusion barriers by electron probe microanalysis and Auger electron spectroscopy

Several electron probe microanalysis and Auger electron spectroscopy profiling techniques were used to characterize diffusion behavior and intermetallic compound formation at diffusion barriers in engine bearings. Four Auger techniques were employed: sputtering, taper sectioning, ball cratering, and cross sectioning with examination by a high resolution electron beam. Cross sections of the bearings were also studied using both scanning and focused‐spot techniques of the electron probe microanalyzer. The advantages and shortcomings of the various preparation and analysis methods are discussed. No single method could adequately characterize the system, but the combination of techniques proved sufficient. The analyses showed current single‐barrier bearings underwent undesired diffusion during engine operation. Results of the chemical composition profiles were mapped onto ternary and quaternary diagrams. These diagrams were used to optimize the relative layer thicknesses in a new trimetal barrier bearing with improved score resistance.