On the Stability of Metastable Precipitates in an Al–1.87 at% Cu Alloy at Elevated Temperature

Abstract

The reversion behaviour of an AlCu(1.87) alloy is investigated by microhardness (HV) measurements and SAXS in dependence on the pre‐ageing temperature (Tpre = RT, 70, and 100 °C) and the pre‐ageing time (0 ≦ tpre ≦ 100 d). The subsequent reversion treatment is performed at Trev = 160 °C. The stability of the metastable precipitates against the reversion at Trev increases with Tpre and in case of constant Tpre with pre‐ageing duration. Therefore it is not possible to determine a fixed solvus line. Partial reversion at Trev = 160 °C doesn't accelerate the rehardening, contrary to the results at Trev = 130 °C. Simultaneously performed TEM investigations support the results of the HV and Q0 investigations.