Official Answer
Answer
Beryllium Copper (typically Alloy 25) is used for retaining rings requiring high electrical conductivity and non-magnetic behavior. It has a high fatigue strength and can be hardened after forming to levels approaching carbon steel ($S_u \approx 1300$ MPa). In electronics, it serves a dual purpose: mechanically retaining components and providing an EMI/RFI shielding path. Its low modulus ($E \approx 128$ GPa) allows for easier installation over shafts without permanent deformation compared to stainless steel.
