Statistical Mapping of Alloy Samples by Spark Excited Optical Emission Spectroscopy

Abstract

Statistical emission maps of ferrous alloy samples were obtained by using stable spark discharge trains for improved sampling resolution. Large changes in emission intensities were observed for matrix and alloying elements as a function of position on the sample. By using several complementary experimental systems, the source of the changes in emission intensities was traced to the sample and was mainly due to changes in the sampling efficiency. Although large changes in emission intensities were observed, there were groups of correlating signals that followed one another. A correlation-based treatment of the emission map data provides analytically useful information including compensating for the sample-dependent changes in erosion of material from the sample electrode.