Qualitative X-ray Analysis of Thin Specimens

Li et al. (2000) have employed nanometer scale analysis in a FEG-TEM operating at 200 kV to distinguish between true GP zones in an Al-Zn-Mg-Cu alloy and GP zone-like defects caused by electron beam irradiation in the TEM. They studied an Al-6.58Zn-2.33Mg-2.40Cu (wt%) alloy, in which it is well known that the decomposition of supersaturated solid solutions takes place via the formation of GP zones, using conventional techniques to produce thin foil specimens of aged material. 

Comparison of the two spectra confirms that there is an enrichment of Zn and Mg in the GP zone in the upper illustration. There is, however, no sign of Zn or Mg enrichment in the GP zone-like defect structure, as shown in the lower spectrum. 

6 Quantitative Analysis of Thin Specimens (Cliff-Lorimer and Methods) 

All quantitative X-ray microanalysis requires that the background Bremsstrahlung be subtracted from the observed spectrum, so that the relative intensities of the characteristic X-rays can be determined. 

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