45Sc nuclear magnetic resonance analysis of precipitation in dilute Al-Sc alloys

Nuclear magnetic resonance (NMR) with Sc-45 is used to determine the solid solubility of scandium in aluminium and to follow the precipitation of Al3Sc during the ageing of an Al-0.06 at.% Sc alloy via the two fully resolved peaks, corresponding to Sc in the solid solution Al matrix and to Sc in the precipitate phase. The ordering of the precipitate phase particles formed during ageing at a sequence of temperatures has been observed. The solvus line of the Al-rich end of the Al-Sc phase diagram is determined by measuring the intensity of the signal from the Sc atoms in the matrix relative to the signal from the Sc atoms in the precipitate phase for an Al-0.29 at.% Sc alloy homogenized at different temperatures. The high detection sensitivity of Sc-45 for NMR is demonstrated.