@article{Gautam2024, 
author = {Prakash C. Gautam and Somjeet Biswas},
title = {Anisotropic FCGR behaviour in hot-rolled Mg-3Al-0.5Ce alloy},
year = {2024},
journal = {Journal of Magnesium and Alloys},
volume = {12},
number = {7},
pages = {2985-3002},
keywords = {Fatigue crack growth rate (FCGR), Magnesium (Mg), Intermetallics, Extension twins, Crack closure},
url = {https://www.sciopen.com/article/10.1016/j.jma.2024.07.017},
doi = {10.1016/j.jma.2024.07.017},
abstract = {In this work, anisotropic fatigue crack growth rate (FCGR) behaviour in a hot-rolled Mg-3wt%Al-0.5wt%Ce alloy was investigated using compact tension (CT) specimens with notch (an) parallel to the rolling direction (RD) and transverse direction (TD). The FCGR tests were conducted at a constant load ratio (R = 0.1) and maximum stress intensity factor (KMax = 15.6 MPa√m) to investigate the crack closure effect. For both constant R and KMax conditions: (i) the load-displacement curves for every loading cycle were linear for an ∥ to RD and TD, indicating no crack closure; (ii) the FCGR was found to be lower for an ∥ RD than an ∥ TD over the entire stress intensity factor range (ΔK). The hot-rolled sample contained long-aligned Al11Ce3 intermetallic phase within grain boundaries that are elongated along RD. During the FCGR test, {1012} {1011} extension twins (ET) with lamellae ∼⊥ and c-axis ∼∥ to these elongated intermetallics along RD developed irrespective of the notch orientation. During the loading cycle, these intermetallics along RD generate back-stresses, reducing the in-plane tensile stress ∼∥ and ∼⊥ to crack-tip to ~ 0 for an ∥ to RD and TD, respectively. Hence, lenticular ET ~⊥ and ~∥, with c-axis ~∥ and ~⊥ to crack path activates, leading to trans and inter lamellar crack for an ∥ to RD and TD, respectively, and anisotropic FCGR. Translamellar crack in an ∥ RD reduces the FCGR due to plastic energy dissipation as perceived by comparatively more geometrically necessary boundaries (GNBs). On the other hand, faster FCGR was obtained for an ∥ TD due to interlamellar cracking. Thus, the crack growth through the matrix-ET interfaces was favoured due to strain incompatibility. The Fractography for an ∥ RD shows smaller elongated grooves along crack propagation, which indicates crack arrest. However, larger elongated grooves for an ∥ TD indicated easy crack propagation due to favourable interlamellar crack.}
}