The contribution of the matrix to the strengthening of dilute Al-Li alloys was determined during the precipitation of the δ' (Al3Li) phase, by means of isothermal hardness curves, from which were obtained the average concentration of solute atoms in the matrix, using a calibration curve giving the hardness of homogeneous solid solutions for different concentrations. At maximum hardening, the exponent q of the additivity rule which gave the solid-solution strengthening, τq = τmq + τpq, where τm and τp were the contributions of the matrix and the δ' phase, respectively, was equal to unity; with an antiphase boundary energy of about 130mJ/m2.

Contribution of the Matrix to the Hardening of Al-Li Alloys during δ' Phase Precipitation. Annales de Chimie: Science des Materiaux, 2007, 32[5], 513-29