About the influence of chromium on the damping capacity of Mn - 40 % Cu alloy in the field of small oscillation amplitudes

The results of a study of the influence of chromium on the damping capacity of manganese- copper alloys in the field of small oscillation amplitudes are presented in the article. High damping alloys based on Mn - Cu can be effectively used to reduce vibration and noise. However, the high damping capacity of these alloys decreases over time. Studies that determine the influence of various alloying elements on the magnitude and stability of the damping capacity of Mn - Cu double alloys in the field of small oscillation amplitudes are not enough. In the work the effect of chromium in concentrations (0.6 … 1.2) % on the damping capacity of the Mn - 40 % Cu alloy in the field of small oscillation amplitudes was elucidated. Manganese-copper alloys were smelted in an induction furnace followed by casting into cast-iron molds. From the melted ingots samples for studies with dimensions (11 × 15× 117) ± 1 mm were obtained by mechanical cutting. During the experiment, the studied samples were subjected to aging at a temperature of 643 K for (0,5 … 40) hours. The change in the damping capacity of manganese-copper alloys (the logarithmic decrement of attenuation of oscillations) was analyzed for longitudinal oscillations of the samples in the frequency range (14 … 17) kHz and the amplitudes of the relative shift (1 … 3) × 10-6. The data obtained indicate that alloying the Mn - 40 % Cu alloy with chromium from 0,6 % to 1,2 % does not increase its damping capacity in the cast state, as well as in the cast and aged at a temperature of 643 K for 40 hours. It was found that the minimum values of the frequencies of resonant vibrations of samples of manganese-copper alloys precede the maximum levels of the damping capacity of these alloys. It’s revealed that the high damping capacity of cast and aged at 643 K for 40 hours alloys Mn - 40 % Cu, Mn - (38,8 … 39,4) % Cu - (0,6 … 1,2) % Cr after natural aging at 293 K for 7 months decreases by (1,6 … 1,9) times.