Microanalysis of Al + 4 wt. % Cu by combined electron microscopy and energy analysis

Direct observations of the energy loss spectra from θ phase precipitates in Al + 4 wt. % Cu alloy have been made by means of combined electron microscopy and energy analysis in order to examine the difficulties involved in using this technique for qualitative microanalysis of precipitated phases. It is concluded that a microanalysis will be completely reliable if the peaks in the characteristic energy loss spectra (0 to 50 ev) from matrix and precipitate are reasonably well defined and well separated. If this is not so, then the precipitate must extend from the top to the bottom surface of the electron microscope specimen before any reliable information can be obtained. As far as the extension of the technique to the study of segregation effects is concerned, it is concluded that the boundaries at which such effects are expected must be aligned parallel to the incident electron beam.