A New Approach to the Determination of Concentration Profiles in Atom Probe Tomography

Abstract

Atom probe tomography (APT) provides three-dimensional analytical imaging of materials with near-atomic resolution using pulsed field evaporation. The processes of field evaporation can cause atoms to be placed at positions in the APT reconstruction that can deviate slightly from their original site in the material. Here, we describe and model one such process--that of preferential retention of solute atoms in multicomponent systems. Based on relative field evaporation probabilities, we calculate the point spread function for the solute atom distribution in the "z," or in-depth direction, and use this to extract more accurate solute concentration profiles.

Grain boundary segregation engineering and austenite reversion turn embrittlement into toughness: Example of a 9 wt.% medium Mn steel

“…Absolute concentrations are easier to understand, but they do not necessarily reflect thermodynamic mechanisms and do not contain changing matrix compositions. An excess value averages the grain boundary composition and is independent of APT reconstruction and evaporation artifacts [20]. Local magnification effects are examples of such effects: these are visible, for example, in Fig.…”

“…Atom probe tomography (APT), with its capability of 3-D analytical mapping of materials at atomicscale resolution and with ppm detection sensitivity for all elements [20][21][22], is an ideal tool with which to quantitatively study grain boundary segregation, even in the initial stage of tempering. Thus, the goal of this work was to quantify grain boundary segregation in Fe-9 wt.% Mn by applying APT to gain a better understanding of the atomistic mechanisms of both solute Mn-driven grain boundary embrittlement and the opposite trend promoted by martensite-to-austenite reversion at interfaces.…”

Atom probe microscopy characterization of as quenched Zr–0.8wt% Fe and Zr–0.15wt% Cr binary alloys

“…2(d), reveals that Fe also segregates to the grain boundary, with a peak concentration of approximately 2.5 at%. The width of the profile, as well as its asymmetry, are most likely affected by preferential retention of Fe [29] or trajectory aberrations. We therefore calculated the Gibbsian interfacial excess, which is less affected by these issues [17,30], in a 120 nm-diameter cylinder positioned perpendicular to the grain boundary that yielded a value of 7.45 at/nm 2 .…”

Mining information from atom probe data

“…However, quantitative analysis of the distribution of the atoms with respect to these features is required for a meaningful interpretation of the data [8,[95][96][97]. While the definition of such objects is an abstraction [98], it is required for improved visualisation or to relate the distribution of the atoms to these features.…”