Fatigue-induced HCP-to-FCC phase transformation assisting crack nucleation of pure zirconium in high cycle fatigue regime

Abstract

This paper investigates the high cycle fatigue behavior of industrial pure zirconium at room temperature under a stress ratio of R = 0.1, focusing on the HCP-to-FCC phase transformation and its role in fatigue crack nucleation. The results show the presence of fatigue damage in the form of the HCP-to-FCC phase transformation, which is responsible for the crack nucleation. The fatigue-induced phase transformation is triggered by the activation and slip of partial dislocations. This phase transformation results in lattice expansion, local strain redistribution, and macroscopic strain. Notably, the strain concentration along the HCP/FCC phase interfaces is identified as a critical factor contributing to fatigue crack nucleation. These findings provide new insights into the mechanisms underlying fatigue-induced phase transformations and the nucleation of fatigue crack.