Atom probe microanalysis of a pearlitic steel

Abstract

A computer-controlled FIM/atom probe mass spectrometer has been used to measure the partitioning of alloying elements between the carbide, matrix, and interface regions of a commercial 0.8C-0.7Mn-0.3 wt.-%Si pearlitic steel, produced by a lead patenting process. The spatial and mass resolution of the instrument permit measurement of the alloying element redistribution over small distances (< 1 nm). The analyses showed the silicon content of the matrix to be twice that of the cementite phase. The manganese level was found to be enriched in a thin (∼1.0 nm) shell at the edge of the cementite phase, while the central region of the cementite had the same manganese level as the matrix. The results of the complete analyses of each region also demonstrated the behaviour of the residual elements Cr, Ni, and Cu. Chromium partitioned to the cementite and interface regions and the residual nickel and copper had higher concentrations in the interface regions.