Al4Cu9

Al4Cu9 is an intermetallic compound in the aluminum-copper system, representing a hard, brittle phase that forms at intermediate copper concentrations. This material is primarily of research and academic interest rather than a widespread commercial alloy, as intermetallics in this composition range are typically too brittle for conventional forming and machining. Its significance lies in understanding phase behavior in Al-Cu systems and in niche applications where high hardness and thermal stability at elevated temperatures are prioritized over ductility.