High purity Cu- 1. 1, 1. 5, 2. 0, and 2. 2 wt pct Be alloys were homogenized at 800 degree C for two hours and quenched in brine prior to 2 hour agings at several temperatures above and below the reported gamma phase boundary. The gamma invariant temperature is higher by at least 10 degree C than the one generally reported. A more realistic value is 620 degree C for the gamma invariant as determined by reversion, and diffraction experiments.
