{"title":"Significant Microstructure Refinement and Improved Mechanical Properties of Mg2Si/Al Composites Induced by Nanoscale TiB2 Particles","authors":"Peng Xiao, Qiqiang Zhao, Wenyu Wu","doi":"10.1007/s11661-024-07487-5","DOIUrl":null,"url":null,"abstract":"<p>Aluminum matrix composite have shown the great prospects in improving service performance and life of high-end equipment under harsh conditions due to lightweight and high specific strength. However, the presence of coarse Mg<sub>2</sub>Si phase with undesired morphology in Mg<sub>2</sub>Si/Al composites limits their engineering application. This study proposes a strategy of TiB<sub>2</sub> ceramic particles regulating the morphology and size of Mg<sub>2</sub>Si to strengthen the aluminum matrix composites by incorporating dual-scale hybrid reinforcements of Mg<sub>2</sub>Si and TiB<sub>2</sub>. The TiB<sub>2</sub> particles were introduced into the Al-15 wt pct Mg<sub>2</sub>Si composite by a master alloy method, and the influence of TiB<sub>2</sub> particles on the morphology and size of Mg<sub>2</sub>Si, and Al grains of composites were investigated. The results demonstrate that 3 wt pct TiB<sub>2</sub> particles can refine the primary Mg<sub>2</sub>Si from 14.6 to 10.4 μm, resulting in a more regular morphology. Additionally, the eutectic Mg<sub>2</sub>Si transforms from a long and slender Chinese character shape to a short rod shape, reducing the aspect ratio by 65.9 pct from 10.9 to 3.7. During the solidification process, TiB<sub>2</sub> particles promote the heterogeneous nucleation of primary Mg<sub>2</sub>Si phases and impede the growth, leading to significant refinement. However, the improved morphology of eutectic Mg<sub>2</sub>Si is mainly attributed to the inhibited preferential growth due to the formation of a nanoparticle layer, with no observed heterogeneous nucleation of TiB<sub>2</sub>. Moreover, TiB<sub>2</sub> particles significantly refine the grain size of Al from 212.7 to 70.8 μm. The addition of 3 wt pct TiB<sub>2</sub> greatly improves the strength of the composites from 302 to 373 MPa, without losing ductility. After T6 heat treatment, Al-15 wt pct Mg<sub>2</sub>Si composites exhibit simultaneous improvement in the strength and ductility. Compared with composites without TiB<sub>2</sub> particles (361 MPa and 32 pct), Al-15Mg<sub>2</sub>Si-3TiB<sub>2</sub> composites have more superior strength–ductility combination of 434 MPa and 35 pct due to the significant modification of Mg<sub>2</sub>Si phase, grain refinement, and Orowan strengthening.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\n","PeriodicalId":18504,"journal":{"name":"Metallurgical and Materials Transactions A","volume":"72 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Metallurgical and Materials Transactions A","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1007/s11661-024-07487-5","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Aluminum matrix composite have shown the great prospects in improving service performance and life of high-end equipment under harsh conditions due to lightweight and high specific strength. However, the presence of coarse Mg2Si phase with undesired morphology in Mg2Si/Al composites limits their engineering application. This study proposes a strategy of TiB2 ceramic particles regulating the morphology and size of Mg2Si to strengthen the aluminum matrix composites by incorporating dual-scale hybrid reinforcements of Mg2Si and TiB2. The TiB2 particles were introduced into the Al-15 wt pct Mg2Si composite by a master alloy method, and the influence of TiB2 particles on the morphology and size of Mg2Si, and Al grains of composites were investigated. The results demonstrate that 3 wt pct TiB2 particles can refine the primary Mg2Si from 14.6 to 10.4 μm, resulting in a more regular morphology. Additionally, the eutectic Mg2Si transforms from a long and slender Chinese character shape to a short rod shape, reducing the aspect ratio by 65.9 pct from 10.9 to 3.7. During the solidification process, TiB2 particles promote the heterogeneous nucleation of primary Mg2Si phases and impede the growth, leading to significant refinement. However, the improved morphology of eutectic Mg2Si is mainly attributed to the inhibited preferential growth due to the formation of a nanoparticle layer, with no observed heterogeneous nucleation of TiB2. Moreover, TiB2 particles significantly refine the grain size of Al from 212.7 to 70.8 μm. The addition of 3 wt pct TiB2 greatly improves the strength of the composites from 302 to 373 MPa, without losing ductility. After T6 heat treatment, Al-15 wt pct Mg2Si composites exhibit simultaneous improvement in the strength and ductility. Compared with composites without TiB2 particles (361 MPa and 32 pct), Al-15Mg2Si-3TiB2 composites have more superior strength–ductility combination of 434 MPa and 35 pct due to the significant modification of Mg2Si phase, grain refinement, and Orowan strengthening.
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