Twinning mediated anisotropic fracture behavior in bioimplant grade hot-rolled pure magnesium  

作　　者：Prakash C.Gautam Somjeet Biswas 

机构地区：[1]Light Metals and Alloys Research Lab,Department of Metallurgical and Materials Engineering,Institute of Technology Kharagpur,Kharagpur,West Bengal 721302,India [2]Institut für Metallkunde und Materialphysik(IMM),Rheinisch-Westfälische Technische Hoschule Aachen,Aachen 52074,Germany

出　　处：《Journal of Magnesium and Alloys》2024年第9期3806-3822,共17页镁合金学报（英文）

基　　金：financial support provided by the Science and Engineering Research Board (Ref. no.: ECR/2016/000125), Department of Science and Technology, Government of India

摘　　要：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 ob-served due to different twin lamellae formation w.r.t.notch owing to the initial basal texture with{10¯10}and{11¯20}poles mostlyand⊥to RD.The out-of-plane tensile stresses activated the{10¯12}||10¯11||extension twins(ET)as usual with matrix-ET∑15b coincident site lattice boundary(CSLB)interfaces.While the in-plane tensile stress⊥to the crack-tip activated{10¯11}||10¯12||contraction twins(CT)that transform into{10¯11}-{10¯12}double twins(DT)with matrix-DT∑23b and∑15a 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∑23b/∑15a CSLB interfaces during FT.While,significant DT and ET lamellae developed at∼0°and∼60°with cracking via the matrix-DT∑23b/∑15a and matrix-ET||15b CSLBs for an⊥RD.The DT and ET lamellae activated at∼15°,and the crack propagated through∑15b 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∑15b interfaces.In contrast,almost similar and higher crack-tip plasticity occurred in matrix and DT domains during crack propagation via||23b/||15a CSLBs.Crack growth through∑23b/||15a led to high JIC,both∑15b and||23b/||15a led to moderate JIC,and∑15b least JIC for an||,⊥and 45°to RD,respectively.

关 键 词：Magnesium Elastic-plastic fracture toughness TWINS Texture Strain incompatibility 

分 类 号：TG146.22[一般工业技术—材料科学与工程]