At least two maxima have been defined in the relatively narrow domain (240 to 280°C, 1 Hz) on the temperature-dependent internal friction curves for the quenched and coldworked austenitic alloys with different chemical composition. The first peak is connected with reorientation of interstitial atoms couples in the applied stresses, the second with the dislocation motion. Analysis of the temperature-dependent internal friction spectrum for heat treated or mechanical treated alloys or both is considered to be difficult.
A new approach for the investigation of this complex spectrum has been developed. Computer simulation of internal friction (IF) peak splitting to a few partial peaks is suggested. The method applied for the splitting of complex IF peaks in the heat treated iron-nickel-molybdenum (Fe-Ni-Mo) alloys is based on different activation energies of diffusion for carbon and nitrogen atoms in face-centered-cubic solid solution. The optimization procedure has been carried out with the use of experiment planning and by searching for the function minimum by the method of steepest descent.
After plastic deformation the IF spectrum of the quenched specimens becomes more compli-cated. The superposition of three IF peaks Qc-1 (carbon), Qn-1 (nitrogen) and strain-induced IF peak Qp-1 takes place.
The results of computer simulation of the IF spectrum as well as the obtained data for activation energies for the heat treated and deformed iron-nickel, iron-nickel-molybdenum, iron-chromium-nickel, and iron-manganese-aluminum alloys are discussed. The influence of the degree of plastic deformation and chemical composition on the IF peak is analyzed on this basis.