000208195 001__ 208195
000208195 005__ 20180913063123.0
000208195 0247_ $$2doi$$a10.1016/j.actamat.2015.01.023
000208195 022__ $$a1359-6454
000208195 02470 $$2ISI$$a000351799300001
000208195 037__ $$aARTICLE
000208195 245__ $$aBrittle and ductile crack-tip behavior in magnesium
000208195 269__ $$a2015
000208195 260__ $$aOxford$$bElsevier$$c2015
000208195 300__ $$a12
000208195 336__ $$aJournal Articles
000208195 520__ $$aThe competition between dislocation emission and cleavage at a crack tip plays an important role in governing the intrinsic fracture behavior of crystalline materials. This competition is not well understood in magnesium, which has many different combinations of cleavage planes and dislocation slip systems. Here, using both anisotropic linear elastic fracture mechanics theory and atomistic simulations, the emission/cleavage competition in magnesium is evaluated for a comprehensive set of crack orientations and crack tip geometries under mode I crack tip stress intensity loading at T= 0 K. Both theory and simulation show that cleavage is favored in most crack orientations, including basal plane cracks, tensile twin and basal-prismatic plane interface cracks. Initial slight crack tip blunting does not significantly change the behavior. These results suggest that magnesium has extremely low intrinsic fracture toughness, consistent with observations of many different cleavage-like planes in low-temperature fracture experiments. Based on T = 0 K properties, obtaining a more-ductile material via crack tip dislocation emission on the pyramidal and basal slip systems would require substantial and moderate reductions of the unstable stacking fault energy (similar to 50% and similar to 20%, respectively) to be achieved at finite temperatures and/or via alloying. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
000208195 6531_ $$aMagnesium
000208195 6531_ $$aCracks
000208195 6531_ $$aDislocations
000208195 6531_ $$aFracture
000208195 6531_ $$aMolecular dynamics simulations
000208195 700__ $$aWu, Z.$$uEcole Polytech Fed Lausanne, Inst Engn Mech, CH-1015 Lausanne, Switzerland
000208195 700__ $$0246474$$aCurtin, W. A.$$g211624$$uEcole Polytech Fed Lausanne, Inst Engn Mech, CH-1015 Lausanne, Switzerland
000208195 773__ $$j88$$q1-12$$tActa Materialia
000208195 8564_ $$s494392$$uhttps://infoscience.epfl.ch/record/208195/files/Brittle_and_Ductile_Crack-ti_pre-print.pdf$$yPreprint$$zPreprint
000208195 909C0 $$0252513$$pLAMMM$$xU12614
000208195 909CO $$ooai:infoscience.tind.io:208195$$pSTI$$particle
000208195 917Z8 $$x222139
000208195 917Z8 $$x241433
000208195 937__ $$aEPFL-ARTICLE-208195
000208195 973__ $$aEPFL$$rREVIEWED$$sPUBLISHED
000208195 980__ $$aARTICLE