Anisotropic FCGR behaviour in hot-rolled Mg-3Al-0.5Ce alloy  

作　　者：Prakash C.Gautam Somjeet Biswas 

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

出　　处：《Journal of Magnesium and Alloys》2024年第7期2985-3002,共18页镁合金学报（英文）

基　　金：support provided by the Science and Engineering Research Board(Ref.no.:ECR/2016/000125);Department of Science and Technology,Government of India.SB acknowledges the funding by Alexander von Humboldt Foundation,Germany.

摘　　要：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 a_(n)∥ 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(△K).The hot-rolled sample contained long-aligned Al11Ce3 intermetallic phase within grain boundaries that are elongated along RD.During the FCGR test,{10.12}<10.11>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 a_(n)∥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 anto RD and TD,respectively,and anisotropic FCGR.Translamellar crack in a_(n)∥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 a_(n)∥TD due to interlamellar cracking.Thus,the crack growth through the matrix-ET interfaces was favoured due to strain incompatibility.The Fractography for a_(n)∥RD shows smaller elongated grooves along crack propagation,which indicates crack arrest.However,larger elongated grooves for a_(n)||TD indicated easy crack propagation due to favourable interlamellar crack.

关 键 词：Fatigue crack growth rate(FCGR) Magnesium(Mg) INTERMETALLICS Extension twins Crack closure 

分 类 号：TG146.22[一般工业技术—材料科学与工程]