Three-dimensional atom probe analysis of heavily drawn steel wires by probing perpendicular to the pearlitic lamellae

Three-dimensional atom probe analysis of heavily drawn pearlitic steel wires was conducted by probing in the direction perpendicular to the pearlitic lamellae. A needle tip perpendicularly intersecting the lamellar structure was prepared using focused ion beam (FIB) milling combined with the lift-out method. The specimen preparation technique enabled the analysis of many lamellae and their interfaces with higher depth spatial resolution, which was suitable for drawn pearlitic steel wires having inhomogeneous and fine lamellar structure. Carbon concentration peaks at the cementite lamellae appeared higher and narrower than those obtained by probing parallel to the lamellae, which implies that the conventional analysis overestimated the extent of cementite decomposition in drawn pearlitic steel wires.