![]() ![]() Wolfgong, in Handbook of Materials Failure Analysis with Case Studies from the Aerospace and Automotive Industries, 2016 3.5 EDS and WDSĮDS is one of the better known methods applied to failure analysis and is also referred to as energy dispersive X-ray (EDX) spectroscopy and even EDAX which was a pioneering company in the development of the method. Spectrum shows expected major elements such as Fe and O due to corrosion products of ferrous base alloy along with minor elements such as Cl, Ca, and Si which were due to contamination. A typical EDS spectrum is shown in Figure 2.4 produced from spring housing failure of tubing retrievable safety valve assembly used in oxygenated water in field location testing for the oil and gas industry. The detection limit for bulk materials is 0.1 wt% therefore EDS cannot detect trace elements (concentrations below 0.01 wt%). EDS can detect major and minor elements with concentrations higher than 10 wt% (major) and minor concentrations (concentrations between 1 and 10 wt%). The detection limit in EDS depends on sample surface conditions, smoother the surface the lower the detection limit. Signals produced in an SEM/EDS system includes secondary and backscattered electrons that are used in image forming for morphological analysis as well as X-rays that are used for identification and quantification of chemicals present at detectable concentrations. Simultaneous SEM and EDS analysis is advantageous in failure analysis cases where spot analysis becomes extremely crucial in arriving at a valid conclusion. Typically, SEM instrumentation is equipped with an EDS system to allow for the chemical analysis of features being observed in SEM monitor. The energy dispersive spectroscopy (EDS) technique is mostly used for qualitative analysis of materials but is capable of providing semi-quantitative results as well. ![]()
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