Structural studies on the alloying behaviour of γ-Mn and the development of a high damping capacity in Mn-Cu alloys

Quenched Mn-Cu alloys undergo an unusual type of phase transformation and form metastable structures. A miscibility gap exists in these alloys, and the stability of the alloy phases is associated with the allotropic form of elemental Mn-atoms beyond the equi-atomic compositions. Quenched Mn-33.4 at% Cu alloy, which corresponds to the centre of the miscibility gap, upon ageing gives rise to a high damping capacity. The internal lattice strain which is the cause of the high damping capacity is thought to be due to interfacial misfit of the MnCu phase and elemental Mn in the proposed metastable structure of the alloy.