Internal friction of Cu–13.5Al–4Ni shape memory alloy measured by dynamic mechanical analysis under isothermal conditions

Abstract

Cu–13.5Al–4Ni shape memory alloy (SMA) exhibits a β 1(DO 3) → β 1′ (18R) internal friction peak with high damping capacity and elevated martensitic transformation temperature in a dynamic mechanical analysis tan δ cooling curve. When the specimen is isothermally maintained at peak temperature, the damping capacity decreases significantly and reaches a steady value. The inherent and intrinsic internal frictions of Cu–13.5Al–4Ni SMA are extremely low because the β 1′ (18R) martensite has an ordered 9R structure with stacking faults rather than twinning with movable twin boundaries.