Nonlinear neck formation in zirconium alloys

The macrolocalization of plastic strain in samples of zirconium alloys with hexagonal close-packed structure under uniaxial tension was studied by laser speckle interferometry and surface profiling. The occurrence of oscillatory instability in the parabolic stage of plastic flow of zirconium alloys was found to be due to a local nonuniform change of the sample shape. The kinetics of process was shown to be determined by oscillatory changes in the contraction and elongation strains at the macrolocalization site in the hardening-softening regime.