Identification of boron in M23X6 precipitates in 316 stainless steel using electron energy loss spectroscopy

The paper concerns the location of boron in carbide precipitates in two casts of 316 steel with varying boron concentrations. Low-resolution location of the boron was performed by secondary ion mass spectrometry. The boron was mostly segregated to the grain boundaries of the steel. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the grain boundaries were heavily coated with precipitates of the carbide M23X6 (M metal, X C, B, N). These precipitates were identified by X-ray energy-dispersive spectroscopy, in both the TEM and SEM, and convergent-beam electron diffraction in the TEM. Electron energy loss spectroscopy was employed to locate the boron within the carbides. The visibility of the boron K edge was enhanced by a digital filtering technique. (author)