title: Atom probe study of vanadium interphase precipitates and randomly distributed vanadium precipitates in ferrite.
abstract: Atom probe tomography and transmission electron microscopy were used to examine the precipitation reaction in the austenite and ferrite phases in vanadium micro-alloyed steel after a thermo-mechanical process. It was observed that only in the ferrite phase precipitates could be found, whereupon two different types were detected. Thus, the aim was to reveal the difference between these two types. The first type was randomly distributed precipitates from V supersaturated ferrite and the second type V interphase precipitates. Not only the arrangement of the particles was different also the chemical composition. The randomly distributed precipitates consisted of V, C and N in contrast to that the interphase precipitates showed a composition of V, C and Mn. Furthermore the randomly distributed precipitates had maximum size of 20 nm and the interphase precipitates a maximum size of 15 nm. It was assumed that the reason for these differences is caused by the site in which they were formed. The randomly distributed precipitates were formed in a matrix consisting mainly of 0.05 at% C, 0.68 at% Si, 0.03 at% N, 0.145 at% V and 1.51 at% Mn. The interphase precipitates were formed in a region with a much higher C, Mn and V content.
authors.affiliation: Christian Doppler Laboratory for Early Stages of Precipitation, Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef-Straße 18, A-8700 Leoben, Austria. Electronic address: matthias.noehrer@unileoben.ac.at.
authors.forename: M
authors.initials: M
authors.lastname: Nöhrer
authors.forename: S
authors.initials: S
authors.lastname: Zamberger
authors.forename: S
authors.initials: S
authors.lastname: Primig
authors.forename: H
authors.initials: H
authors.lastname: Leitner
keywords: Atom probe tomography; Interphase precipitates; Micro-alloyed; Steel; Vanadium