BRUSH CASTING ALLOYS 275C AND 275CT are beryllium copper alloys of very high strength with cobalt and silicon as the secondary alloying elements. Use is in the age-hardened temper. Brush casting alloy 275CT is the fine-grained version. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Cu-537. Producer or source: Brush Wellman Inc.. Originally published as Brush Wellman Alloy 275C, 275CT, April 1988, revised December 1992.