Amplitude dependence of the internal friction in a Pb-62% Sn alloy

The method of forced flexural vibrations is used to obtain the amplitude dependence of the internal friction (Q−1(ɛ0)) in the Pb-62% Sn alloy, which exhibits superplasticity at room temperature. A phenomenological model of the internal friction, in which the plasticity of alloys is considered as a hybrid relaxation-hysteresis process, is proposed. The numerical values of the cyclic-strain-hardening exponent n of the Pb-62% Sn alloy are determined in the microplastic and superplastic states, and the nature of the experimentally detected asymmetric maximum in Q−1(ɛ0) is discussed.