Atom Probe Tomography II. The Precipitation in Al Base Alloys

This paper presents two illustrations of the study of phase separation in Al-based alloys by means of tomographic atom probe. In an AlMgSi alloy, calculations of pair correlation functions have revealed that the nature of solute short range order differs from a pre-aged specimen to a non-pre-aged specimen. This results in different responses to aged hardening treatments. Concerning Al-3(Zr,Sc)-type disperoids observed in another Al-based alloy, they are found to display a core-shell structure wherein Zr is mainly present in the disperoids periphery. This duplex structure is likely to explain the relative stability of Al-3(Zr,Sc) disperoids.