V.M. Andronov’s research while affiliated with Dnipro University of Technology and other places

Fe-Al alloys containing 25 and 31.5 at. % Al have been studied by internal friction, X-ray diffraction and dilatometric analyses. These techniques show for the first time that two internal friction peaks appear during the change in long range order type which occurs during the precipitation at 300degreesC of the metastable phase B2(FeAl). These peaks correspond to the formation of two phases : the equilibrium phase Fe3Al and a new intermediate tetragonal phase theta.

Fe-Al alloys containing 25 and 31.5 at. % Al have been studied by internal friction, X-ray diffraction and dilatometric analyses. These techniques show for the first time that two internal friction peaks appear during the change in long range order type which occurs during the precipitation at 300°C of the metastable phase B2(FeAl). These peaks correspond to the formation of two phases: the equilibrium phase Fe$_3$Al and a new intermediate tetragonal phase $\theta$.

The method of intemal friction has important perspectives in the study of microprocesses slticlt occur during structural transformation in materials. In the present work we show the large possibilities of this type of study in the investigation of anomalous and non linear eltects due to trarrsistorl'processes. A new method of study of the anomalous effects of intemal friction entirely rr'alised in laboratory, is proposed and its possibilities are illustrated on Fe-1.7 wt% C and Fe-wt% Ni alloy (lnvar). On the latter a new peak of intemal friction is observed for the first time.

A method for studying microplasticity of metallic materials based on in situ measurement of internal friction at low sonic frequencies (f similar to 100 Hz) is described. The method uses a relaxometer consisting of a torsional pendulum and a reversible twisting device with a Pi-shaped grip, which allows one to induce strain in relatively thick specimens of diameter to 3 - 4 mm and to measure the residual strain gamma(r) after a cycle of alternating torsion and half-cycles of repeated (of the same sign) torsion.