Application of isothermal upset for megaplastic deformation of Cu–Ni–Al $\beta$ alloys

Cu–14 wt% Al–4 wt% Ni alloy demonstrating the shape memory effect has been subjected to plastic deformation by means of uniaxial compression (upset). The process has been controlled by measuring the strain rate, applied stress, and compression ratio of standard specimens under isothermal conditions in the interval 400–600$^\circ$C. Structural modifications in the alloy after mechanical tests have been studied by optical, scanning, and transmission microscopy methods and using X-ray phase analysis. It has been found that grains in the alloy became much finer (from 1 mm to 100 $\mu$m across) and its strength and ductility improved owing to dynamic recrystallization.