Shock wave study of precipitation hardening of beryllium copper

Based on three series of planar impact tests performed on beryllium copper samples, having thickness 0.25–6 mm, individual contributions of beryllium clusters (in the as quenched supersaturated solid solution), Guinier-Preston zones (GP, formed following ageing at 300°C for 26 min) and metastable γ" precipitates (crystallizing after 400 min ageing at 300°C) to the strength of alloy were quantified along with corresponding activation volumes. These data being coupled with Transmission Electron Microscopy evaluation of geometry and statistics of GP and γ" precipitates, made determination of the resistance τp to dislocation motion (Peierls stress) of the lattices of these particles possible. The great difference between values measured in these two cases, namely 3.7 GPa for GP and 1.4 GPa for the γ" precipitates may be considered as an additional confirmation of the fact that in these two cases the strengthening occurs due to different phases.