Beralcast 191 is a castable beryllium aluminum alloy used to produce near-net-shaped investment cast mirror substrates. The material is 20% lighter and three times stiffer than aluminum. The material also has a damping coefficient for stability six to ten times better than that of aluminum. Applications include head-mounted mirrors, fire-control reflective optics, night vision, and scanner systems. The material has thermal stability of 0.12 wave rms over a 6-in. aperture for temperatures from -45°F to 135°F.
Starmet Corp., Concord, MA