Complex Precipitation Pathways in Multi-Component Alloys

One usual way to strengthen a metal is to add alloying elements and to control the size and the density of the precipitates obtained. However, precipitation in multicomponent alloys can take complex pathways depending on the relative diffusivity of solute atoms and on the relative driving forces involved. In Al-Zr-Sc alloys, atomic simulations based on first-principle calculations combined with various complementary experimental approaches working at different scales reveal a strongly inhomogeneous structure of the precipitates: owing to the much faster diffusivity of Sc compared with Zr in the solid solution, and to the absence of Zr and Sc diffusion inside the precipitates, the precipitate core is mostly Sc-rich, whereas the external shell is Zr-rich. This explains previous observations of an enhanced nucleation rate in Al-Zr-Sc alloys compared with binary Al-Sc alloys, along with much higher resistance to Ostwald ripening, two features of the utmost importance in the field of light high-strength materials

Precipitation of niobium carbides in Fe–C–Nb steel

International audienceThe precipitation of carbides in Fe-C-Nb alloy has been investigated using field ion microscopy and atom probe tomography. Analyses show that niobium carbide precipitates already exist in the state quenched from 1240degreesC. Detailed structural analysis of the states aged at 750degreesC reveals the existence of two types of niobium carbide precipitates with different concentrations of carbon. In addition, the direction of the habit plane for the matrix/niobium carbide interface has been determined. Copyright (C) 2004 John Wiley Sons, Ltd

Precipitation of niobium carbides in Fe–C–Nb steel

International audienceThe precipitation of carbides in Fe-C-Nb alloy has been investigated using field ion microscopy and atom probe tomography. Analyses show that niobium carbide precipitates already exist in the state quenched from 1240degreesC. Detailed structural analysis of the states aged at 750degreesC reveals the existence of two types of niobium carbide precipitates with different concentrations of carbon. In addition, the direction of the habit plane for the matrix/niobium carbide interface has been determined. Copyright (C) 2004 John Wiley Sons, Ltd

Atom probe tomography I. Early stages of precipitation of NbC and NbN in ferritic steels

International audienceThe results reported in this paper give new information regarding the early stages of precipitation in model low niobium steels. It clearly appears that the kinetic paths for carbides and nitrides precipitation in the investigated model alloys are very different, more continuous in the case of carbides, and through GP zones formation in the case of nitrides

Atom Probe Tomography in Materials Science

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Atom probe tomography study of homogeneous and heterogeneous precipitation of niobium carbides in a model ferritic steel

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Atom Probe Tomography in Materials Science

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Atom probe tomography study of homogeneous and heterogeneous precipitation of niobium carbides in a model ferritic steel

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Effects of incidence angles of ions on the mass resolution of an energy compensated 3D atom probe

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