Uncertainty and statistics of dislocation-precipitate interactions on creep resistance

To meet the 30,000-h design lifetime of a typical turbine disc, understanding of long-term creep behavior is critical to prevent premature structural failure. The existing creep-life predictions often belittle the importance of multiple dislocation-precipitate interactions, resulting in several-orders-of-magnitude deviations in comparison with experiments. Herein, our experimental observation shows precipitate spatial distribution to yield uncertainty of dislocation-precipitate interactions and precipitate-size lognormal distribution to cause coexistence of climb, cutting, and Orowan mechanisms. Accounting for this physical process, we establish a unified model without adjustment parameters for predicting the stress-sensitive creep rate in precipitate-strengthened alloys. The predicted creep rates show agreement with experimental data, which makes up for the flaw of typical classic models with great deviations. Moreover, the present work reveals the stress-controlled transformation of multiple creep mechanisms and evaluates their weighting of creep-resistance contributions. Thus, our model provides insights for accurate design of high-strength and high-creep-resistant alloys under complex service environments.