Monitoring Precipitation during Rapid Quenching of Aluminium Alloys by Calorimetric Reheating Experiments

Abstract

Several age hardening aluminium alloys, like high alloyed 2XXX, 6XXX and 7XXX alloys require high critical quenching rates of some 100 K/s from solution annealing to suppress premature precipitation and achieve maximum strength after aging. Knowledge of the precipitation behaviour during quenching is crucial for the design of quenching processes of aluminium alloys. For monitoring the precipitation behaviour during moderate quenching, a calorimetric method (0.01 to 5 K/s) has already been successfully developed. New Differential Fast Scanning Calorimeters (DFSC, up to some 10(6) K/s) allow rapid quenching of aluminium alloys, but due to weak precipitation reactions the quenching results can hardly be evaluated. Hence, a new method has been developed, to monitor precipitation during rapid quenching of aluminium alloys by calorimetric reheating experiments. Quenching and reheating experiments of high alloyed, quench sensitive aluminium alloys, like 7049A will be presented.