STABLE NONLINEAR RELAXATIONS IN A MULTIPHASIC Al-Zn ALLOY
(Institute of Solid State Physics; Academia Sinica; Hefei 230031; China)
Abstract: The experiments reveal the characteristics of stable damping in a multiphasic Al-Zn eutectoid alloy:(1)The whole damping(Q-1)has the same dependence on measured frequency(f),i.e.Q-1ocf-n,where n is a parameter and is independent of temperature.(2)In a low-temperature(low-T)and low-strain-amplitude(low-A_)region, Q-1=(B/)exp(-nH/kT),where B is a parameter,H the atomic diffusion activation energy,k Boltzmann′s constant,and T the absolute temperature.n,H_o(=nH)and H are all independent of A_.The damping comes from an anelastic motion of the phase-interface.(3)In an intermediate region including a low-Tand a high-A_, a middle-T and middle A_ and a high-T and low-A_ regions,the equation Q-1=(C/fn)exp(nH/kT)still holds,but the damping has a normal amplitude effect C,n,and H all vary with A_;the damping results from a nonlinear relaxation of phase-interface.(4)In a high-T and high-A_ region,there is no longer a linear relation ship between InQ-1 and T-1,whereas the relat...更多ion Q-1f-n is still satisfied,where n increases as A_ increases,and the damping has a normal amplitude effect but one which is weaker than that in the case(3).The damping may be attributed to another kind of nonlinear relaxation between phase-interfaces.
Key words: non-linear; relaxations Al-Zn alloy; damping