Crystallographic orientation effects in energy dispersive X-ray analysis

The circumstances under which EDX microanalysis can yield serious errors as a function of the crystallographic orientation are discussed. It is shown that such errors can be as high as 50° when examining a fully ordered alloy or compound. Experimental results obtained on CuPt are correlated with a theoretical treatment demonstrating both the necessity in such calculations of considering Bloch wave summation effects and that the small value of the impact parameter thus inferred is consistent with a simple time-dependent perturbation treatment of the inelastic scattering process. The reasons why localization effects should be less apparent in energy loss than in EDX measurements are also considered.