{"title":"Anisotropic FCGR behaviour in hot-rolled Mg-3Al-0.5Ce alloy","authors":"","doi":"10.1016/j.jma.2024.07.017","DOIUrl":null,"url":null,"abstract":"<div><p>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 (<em>a<sub>n</sub></em>) parallel to the rolling direction (RD) and transverse direction (TD). The FCGR tests were conducted at a constant load ratio (<em>R</em> = 0.1) and maximum stress intensity factor (<em>K<sub>Max</sub></em> = 15.6 MPa√<em>m</em>) to investigate the crack closure effect. For both constant <em>R</em> and <em>K<sub>Max</sub></em> conditions: (i) the load-displacement curves for every loading cycle were linear for <em>a<sub>n</sub></em> ∥ to RD and TD, indicating no crack closure; (ii) the FCGR was found to be lower for <em>a<sub>n</sub></em> ∥ RD than <em>a<sub>n</sub></em> ∥ TD over the entire stress intensity factor range (Δ<em>K</em>). The hot-rolled sample contained long-aligned Al<sub>11</sub>Ce<sub>3</sub> intermetallic phase within grain boundaries that are elongated along RD. During the FCGR test, <span><math><mrow><mrow><mo>{</mo><mrow><mn>10</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>2</mn></mrow><mo>}</mo></mrow><mrow><mo>〈</mo><mrow><mn>10</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>1</mn></mrow><mo>〉</mo></mrow></mrow></math></span> extension twins (ET) with lamellae ∼⊥ and c-axis <span><math><mrow><mo>∼</mo><mo>∥</mo></mrow></math></span> 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 <span><math><mrow><mo>∼</mo><mo>∥</mo></mrow></math></span> and <span><math><mrow><mo>∼</mo><mi>⊥</mi></mrow></math></span> to crack-tip to <span><math><mrow><mo>∼</mo><mn>0</mn></mrow></math></span> for <em>a<sub>n</sub></em> ∥ to RD and TD, respectively. Hence, lenticular ET <span><math><mrow><mo>∼</mo><mi>⊥</mi></mrow></math></span> and <span><math><mrow><mo>∼</mo><mo>∥</mo></mrow></math></span>, with c-axis <span><math><mrow><mo>∼</mo><mo>∥</mo></mrow></math></span> and <span><math><mrow><mo>∼</mo><mi>⊥</mi></mrow></math></span> to crack path activates, leading to trans and inter lamellar crack for <em>a<sub>n</sub></em> ∥ to RD and TD, respectively, and anisotropic FCGR. Translamellar crack in <em>a<sub>n</sub></em> ∥ 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 <em>a<sub>n</sub></em> ∥ TD due to interlamellar cracking. Thus, the crack growth through the matrix-ET interfaces was favoured due to strain incompatibility. The Fractography for <em>a<sub>n</sub></em> ∥ RD shows smaller elongated grooves along crack propagation, which indicates crack arrest. However, larger elongated grooves for <em>a<sub>n</sub></em> ∥ TD indicated easy crack propagation due to favourable interlamellar crack.</p></div>","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":null,"pages":null},"PeriodicalIF":15.8000,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2213956724002561/pdfft?md5=59443f4cbccf173faa328a9d79a5cc4d&pid=1-s2.0-S2213956724002561-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Magnesium and Alloys","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2213956724002561","RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"METALLURGY & METALLURGICAL ENGINEERING","Score":null,"Total":0}
引用次数: 0
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, 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 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.
期刊介绍:
The Journal of Magnesium and Alloys serves as a global platform for both theoretical and experimental studies in magnesium science and engineering. It welcomes submissions investigating various scientific and engineering factors impacting the metallurgy, processing, microstructure, properties, and applications of magnesium and alloys. The journal covers all aspects of magnesium and alloy research, including raw materials, alloy casting, extrusion and deformation, corrosion and surface treatment, joining and machining, simulation and modeling, microstructure evolution and mechanical properties, new alloy development, magnesium-based composites, bio-materials and energy materials, applications, and recycling.