32 research outputs found
An improved reconstruction procedure for the correction of local magnification effects in three-dimensional atom-probe
A new 3DAP reconstruction procedure is proposed that accounts for the
evaporation field of a secondary phase. It applies the existing cluster
selection software to identify the atoms of the second phase and, subsequently,
an iterative algorithm to homogenise the volume laterally. This Procedure,
easily implementable on existing reconstruction software, has been applied
successfully on simulated and real 3DAP analyses
Precipitate stability and recrystallisation in the weld nuggets of friction stir welded Al-Mg-Si and Al-Mg-Sc alloys
Two different precipitate hardening aluminium alloys processed by friction
stir welding were investigated. The microstructure and the hardness of the as
delivered materials were compared to that of the weld nugget. Transmission
electron microscopy observations combined with three-dimensional atom probe
analyses clearly show that \beta;" precipitates dissolved in the nugget of the
Al-Mg-Si giving rise to some supersaturated solid solution. It is shown that
the dramatic softening of the weld could be partly recovered by post-welding
ageing treatments. In the Al-Mg-Sc alloy, Al3Sc precipitate size and density
are unchanged in the nugget comparing to the base metal. These precipitates
strongly reduce the boundary mobility of recrystallised grains, leading to a
grain size in the nugget much smaller than in the Al-Mg-Si alloy. Both coherent
and incoherent precipitates were detected. This feature may indicate that a
combination of continuous and discontinuous recrystallisation occurred in the
weld nugget
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
An improved reconstruction procedure for the correction of local magnification effects in 3D Atom Probe
International audienc
An improved reconstruction procedure for the correction of local magnification effects in three-dimensional atom-probe
International audienceA new 3DAP reconstruction procedure is proposed that accounts for the evaporation field of a secondary phase. It applies the existing cluster selection software to identify the atoms of the second phase and, subsequently, an iterative algorithm to homogenise the volume laterally. This Procedure, easily implementable on existing reconstruction software, has been applied successfully on simulated and real 3DAP analyses
An improved reconstruction procedure for the correction of local magnification effects in 3D Atom Probe
International audienc