A microstructural investigation of the shear distortions and energetics of motions observed in an aged high damping 53Cu-45Mn-2Al alloy

Abstract

The shear distortions developed upon aging of a 53Cu-45 Mn-2Al alloy were studied using transmission electron microscope image extinctions and diffraction spot streak analysis. It was determined that a lattice distortion of (110) planes, in 111 directions developed in the alloy as aging progressed. This matured 111 shear induces a distinct V-shaped contrast which displays dynamic motion under the electron-beam irradiation of TEM examination. Video imaging techniques were applied to this activity, termed 'flickering', to investigate the energetics of the underlying crystalline lattice motion. The real-time behavior at the flicker sites suggests that the underlying mechanism which produces the dynamic contrast change is a gradual crystallographic transition, typical of a second-order phase transition.