Co-strengthening contribution of δ′ and T1 precipitates in Al-Li alloys 2090 and 2090 + Ce

The microstructure of dislocation in two kinds of aluminum-lithium alloys 2090 and 2090 + Ce was observed by means of TEM technology. The contributions of δ′ and T1 precipitates to strength were separately calculated by using the results of quantitative metallography and analysis of micro-deformation behavior; the co-strengthening effect of δ′ and T1 precipitates was studied. The results show that the adding relationship of co-strengthening of δ′ and T1 is in accordance with q = 1.4 form at the near peak-aged condition, i.e., Δτp1.4 = Δτδ′1.4 but the adding relationship is approximately a linear relation (q = 1) at the under-aged condition and becomes the parabola form when over-aged (q = 2). The adding relationship of co-strengthening contribution of δ′ and T1 is obviously dependent on aging time.