Double Steady-State Creep Behavior in Solid-Solute-Strengthened Zircaloy-4

Long-term creep tests on the solid-solute-strengthened zirconium alloy, i.e., Zircaloy-4, revealed presence of double steady-state behavior at 623–673 K. The first steady state manifested as a faster strain rate (ε) ∼0.05, and second appeared with slower ε > 0.1. Several electron microscopy change in dislocation structure during from motion individual dislocations to generation cell structure. Along this change, stress exponent differed each state, increasing 6.7 10 state. temperature dependency also changed because apparent activation energies were 201 298 kJ/mol for states, respectively. These results show that pipe diffusion self-diffusion are rate-controlling processes Because such changes deformation mechanism one curve highly unusual, is characteristic feature high-temperature Zircaloy-4. For engineering, observation necessary estimating time-to-rupture by means Monkman–Grant relationship rates deviate relationship.