@article{Gautam2024, 
author = {Prakash C. Gautam and Somjeet Biswas},
title = {Twinning mediated anisotropic fracture behavior in bioimplant grade hot-rolled pure magnesium},
year = {2024},
journal = {Journal of Magnesium and Alloys},
volume = {12},
number = {9},
pages = {3806-3822},
keywords = {Magnesium, Elastic-plastic fracture toughness, Twins, Texture, Strain incompatibility},
url = {https://www.sciopen.com/article/10.1016/j.jma.2024.09.013},
doi = {10.1016/j.jma.2024.09.013},
abstract = {Bioimplant grade hot-rolled magnesium with equiaxed microstructure and basal texture was examined for fracture toughness (FT) anisotropy using fatigue pre-cracked single-edge notch bending specimens with the notch, an ||, ⊥ and 45° to rolling direction (RD). Due to adequate crack-tip plasticity, the size-independent elastic-plastic fracture toughness (JIC) were determined. Anisotropic JIC was observed due to different twin lamellae formation w.r.t. notch owing to the initial basal texture with  {101¯0} and  {112¯0} poles mostly || and ⊥ to RD. The out-of-plane tensile stresses activated the  {101¯2}⟨101¯1⟩ extension twins (ET) as usual with matrix-ET Σ15b coincident site lattice boundary (CSLB) interfaces. While the in-plane tensile stress ⊥ to the crack-tip activated  {101¯1}⟨101¯2⟩ contraction twins (CT) that transform into  {101¯1}- {101¯2} double twins (DT) with matrix-DT Σ23b and Σ15a CSLBs. For an || RD, large DT lamellae fraction formed at ~30° and few ETs at ~30° and ~90° to the notch with crack growth mainly via the Σ23b/Σ15a CSLB interfaces during FT. While, significant DT and ET lamellae developed at ~0° and ~60° with cracking via the matrix-DT Σ23b/Σ15a and matrix-ET Σ15b CSLBs for an ⊥ RD. The DT and ET lamellae activated at ~15°, and the crack propagated through Σ15b for an ~45° to RD. The JIC and the crack-tip plastic zone decreases, while the elastic component of the J-integral (Jel) and the ET formation increases from an ||, ⊥,  to ~45° to RD. The strain incompatibility of matrices was higher with the geometrically hard ETs than DTs. Thus, brittle interlamellar cracking occurred through the Σ15b interfaces. In contrast, almost similar and higher crack-tip plasticity occurred in matrix and DT domains during crack propagation via Σ23b/Σ15a CSLBs. Crack growth through Σ23b/Σ15a led to high JIC, both Σ15b and Σ23b/Σ15a led to moderate JIC, and Σ15b least JIC for an ||, ⊥ and 45° to RD, respectively.}
}