Session: MF-09-01 Mechanistic Modelling of Deformation and Fracture

Paper Number: 154357

154357 - The Fracture Mechanics of Zirconium Hydrides: Twinning at Microcrack Tips 

Abstract: 

Zirconium alloys are susceptible to hydrogen embrittlement due to the formation of zirconium hydrides. The transformation strain from hydride precipitation contributes to the initiation of microcracks, adding to the complexity of modeling hydrides cracking. While various deformation mechanisms such as slip and deformation twinning influence the fracture of hydrides, the role of deformation twins at hydride crack tips is less understood. This study focuses on the formation of twins at crack tips and their effect on the fracture behavior of zirconium hydrides. Crystal plasticity finite element (CPFE) modeling and extended finite element method are used for this analysis, where the measured grain orientations by electron backscatter diffraction (EBSD) are mapped to the CPFE models.

In-situ tensile experiments inside a scanning electron microscope, and ex-situ experiments, along with CPFE modeling are used to analyze crack initiation and propagation. The effects of hydride morphology, grain neighborhood, and transformation strain were considered, with a specific focus on hydride-twin interactions at crack tips.

Real-time in-situ observations revealed that deformation twins nucleate at crack tips and propagate with further deformation. The combined CPFE and XFEM models demonstrated that twin propagation at crack tips of hydrides influences stress distribution, potentially delaying crack growth. This study shows the importance of incorporating twin-crack interactions in modeling the fracture of zirconium hydrides.

Presenting Author: Saiedeh Marashi Western university

Presenting Author Biography: I am a fourth-year PhD student at Western University, nearing graduation under the supervision of Dr. Hamidreza Abdolvand. My research focuses on the micromechanics of deformation and fracture in zirconium hydrides, utilizing techniques such as crystal plasticity finite element modeling, in-situ SEM and ex-situ experiments, and electron backscattered diffraction. I have published four papers: one in the Journal of Nuclear Materials (JNM), two in Acta Materialia (2023 and 2024), and one in the International Journal of Plasticity (IJP).

Authors:

Saiedeh Marashi Western university
Brandon Kuo Western university
Hamidreza Abdolvand Western university