Small-Angle X-ray Scattering Study of the Interfacial Characteristics Between δ' Phase and Matrix in Al–2.70 mass% Li Alloy

Small-angle X-ray scattering (SAXS) has been used to study the δ′ precipitation in an Al-2.70 mass% Li alloy aged at 463 K for 8 and 30 h. It is shown that the SAXS profile does not agree with Porod's law and has a negative slope. This suggests that the dispersive interfacial layer exists between the δ′ phase and the matrix. It is positive evidence that spinodal decomposition takes place during the precipitation process of the δ′ phase. The thicknesses of the interfacial layers are found to be 4.75 and 6.63 nm for the samples aged at 463 K for 8 and 30 h, respectively.