Viscoplastic behavior of ultrafme-grained alloys
Features of mechanical behavior of ultrafrne-grained (UFG) titanium and aluminum alloys under quasi-static and shock wave loading with amplitudes up to 10 GPa were studied by the numerical simulation method. To describe viscoplastic behavior of alloys, a multilevel model is offered. The model takes into account several structural factors influencing the mechanical behavior of coarse-grained and UFG alloys. The results display that the strain rate sensitivity of the yield stress of UFG and poly crystalline titanium alloys is significantly different in the range from 10<sup>-3</sup> to 10<sup>6 </sup>s<sup>-1</sup>. The visco-plastic behavior of UFG FCC and HCP alloys is shown to be different at high strain rates.