An atom probe characterisation of grain boundaries in an aluminium alloy processed by equal-channel angular pressing

Abstract

AbstractThe segregation of solute elements at the grain boundaries of an Al–Zn–Mg–Cu alloy processed by equal-channel angular pressing was characterised using three-dimensional atom probe tomography. The results show that Mg and Cu segregate strongly to the grain boundaries but Zn shows no clear segregation and even becomes depleted near the boundaries. Trace elements such as Zr, Cr, Si and Mn show no clear segregation at the grain boundaries. An increase in the number of passes leads to a decrease in the grain size but there is no clear effect on the levels of solute segregation at the boundaries. The significant segregation of certain major alloying element at the boundaries of ultrafine-grained alloys implies that the less super-saturation solutes in the matrix will be available for precipitation with a decrease in the average grain size.