A Novel Method of Analytical Transmission Electron Microscopy for Measuring Highly Accurately Segregation to Special Grain Boundaries or Planar Interfaces

摘要

A new technique of analytical transmission electron microscopy has been developed for determining accurately the amount of solute atoms incorporated into well-defined planar defects in solids, such as stacking faults, special grain boundaries or interfaces. The method is based on recording series of analytical spectra taken with different electron beam diameters on the same position centred above a defect that is oriented nearly edge-on. The matrix/solute ratio is then plotted as a function of the electron beam radius, linear regression is performed and the segregation level is determined from the slope of the best fit. This method can be applied to energy-dispersive X-ray (EDX) or electron energy-loss spectroscopy (EELS) in a transmission electron microscope. It necessitates a nano-probe mode but no scan unit. Reliability and accuracy have been tested numerically. Simulations suggest an accuracy in the determination of the Gibbsian solute excess at a special grain boundary down to ±0.1 atoms nm−2 under typical experimental conditions, with a maximum error about twice as large.