Internal friction in high manganese-content Mn–Cu based alloys

Mn-Cu binary alloys with high manganese content exhibit enhanced damping capacity, a broader temperature window for noise and vibration reduction, and low cost. However, they are significantly hindered by poor workability, elongation, and corrosion resistance. To enhance the poor workability, elongation, and corrosion resistance of high manganese Mn-Cu binary alloys, alloying with Cr is an effective approach. This work investigates microstructure evolution, amplitude-independent thermally-activated, and transient effects (in a temperature range from -90 °C to 200 °C and frequencies from 0.1 Hz to 10 Hz) in high manganese Mn-(10-13)Cu-(0-6)Cr alloys with different Cr contents. The relaxation activation energy for as-water quenched Mn-13Cu binary alloy is 0.56±0.05 eV. The substitution of Cu or Mn by Cr results in an increase in the activation energy. Phase transitions upon heating and cooling are characterized by modulus softening due to shear phase transition in all analyzed samples before and after ageing, while the transient internal friction peaks are observed not in all structural states. An increase in the volume effect of phase transition leads to an increase in the transitory peaks width and area under the peaks in Mn-10Cu-4Cr compared with Mn-13Cu.