Complex irregular stacking faults within Zr3Ge secondary phase nanoparticle stimulated by face-centered cubic zirconium phase growth

Here we report, for the first time, complex irregular stacking faults were generated within tetragonal Zr₃Ge secondary phase particles (SPPs) in the Ge-modified Zircaloy-4 (Zr-4) alloy when subjected to high-temperature compression at 600°C. Atomic-scale observations indicated that the complex irregular stacking faults (CISFs) exhibit a non-coplanar deformation configuration characteristic. When viewed along the [001]_Zr3Ge direction, atomic shifts were observed on three different crystallographic planes: (100), (010) and (110) planes, in other words, this defect was developed by the repetition and connection of superlattice intrinsic stacking faults on three different planes of the Zr₃Ge SPP. Based on the crystallographic orientations relationships among the Zr₃Ge and its surrounding precipitates, a mechanical model was proposed to uncover the nature of such CISFs structure. It confirmed that the CISFs can be attributed to the combined effects of the relatively low stacking fault energy and the growth of two nearby FCC-Zr phases.