Investigation of a solid-state transformation of dispersed intermetallic particles in aluminium alloy from an Al6(Fe,Mn) phase to an α-Al(Fe,Mn)Si phase

Isothermal heat-treatments, at 500°C and lasting from 1 minute to 8 days, were carried out on samples made from a directionally solidified model Al-0.5wt.%Fe1.0wt.%Mn-0.2wt.%Si alloy. Backscattered imaging was performed on polished specimens in an EDX-equipped JEOL 5800LV SEM (working at 10 kV). The in-lens secondary electron detector of a JEOL 6340F FEGSEM (working at 20 kV) was used to examine specimens that were ‘deep etched’ in NaOH solution, an etchant that dissolves aluminium.