Grain boundary precipitate induced PFZ formation to improve the ductility of extruded Mg-Gd-Y-Nd-Zr alloy after ageing

Abstract

An increase in RE element content in Mg alloys promotes the grain boundary precipitate, which affects the mechanical properties. However, the influence of grain boundary precipitates on microstructure of Mg-RE alloys during ageing and their role on ductility of the aged alloy is unclear. In this work, hot extrusion and ageing treatment were performed for Mg-9Gd-2Y-xNd-0.2Zr (x=1 wt.% and 3 wt.%) alloys, and grain boundary precipitates were formed in the extruded Mg-9Gd-2Y-3Nd-0.2Zr alloy due to the increase of Nd content. The extruded alloys exhibit a complete dynamic recrystallization (DRX) microstructure and a texture with the <0001> orientation parallel to the extrusion direction (ED). In addition, a large amount of fiber microstructures distributed by the second phase along the ED were formed in the Mg-9Gd-2Y-3Nd-0.2Zr alloy, while only a small amount of the second phase was observed in the Mg-9Gd-2Y-1Nd-0.2Zr alloy. After ageing treatment, a large amount of β′ phase precipitated inside the grains. The strength of the Mg-9Gd-2Y-1Nd-0.2Zr alloy increased from 202 MPa to 275 MPa but the elongation decreased from 12.8% to 2.6%, and the strength of the Mg-9Gd-2Y-3Nd-0.2Zr alloy increased from 212 MPa to 281 MPa but the elongation decreased from 13.7% to 6.2%. Among them, the Mg-9Gd-2Y-3Nd-0.2Zr alloy showed good overall mechanical properties, especially the elongation of the aged alloy was 58% higher than that of the Mg-9Gd-2Y-1Nd-0.2Zr alloy. The increase in ductility of the aged Mg-9Gd-2Y-3Nd-0.2Zr alloy attributed to the grain boundary precipitate promotes the formation of a large number of precipitation free zones (PFZs) with widths of 130–150 nm during ageing treatment.

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References

[1] ChenC-x, HuoQ-h, ZhangZ-r, et al.. Effects of precipitate origin and precipitate-free zone development on the tensile creep behaviors of a hot-rolled Mg-13wt% Gd binary alloy. Materials Characterization, 2021, 178: 111303 J]

[2] ChiY-q, LiuJ-w, ZhouZ-j, et al.. Investigation on the microstructure, texture and mechanical properties of Mg-Gd-Y(-Zn)-Zr alloys under indirect extrusion. Journal of Alloys and Compounds, 2023, 943: 169061 J]

[3] GaoZ-x, LiuC-m, JiangS-n, et al.. Analysis of abnormal texture and strengthening mechanisms of extruded Mg-Gd-Y-Nd-Zr alloy. Advanced Engineering Materials, 2023, 25(3): 2201046 J]

[4] HengX-w, ZhangY, RongW, et al.. A super high-strength Mg-Gd-Y-Zn-Mn alloy fabricated by hot extrusion and strain aging. Materials & Design, 2019, 169: 107666 J]

[5] JinX-z, XuW-c, YangZ-z, et al.. Analysis of abnormal texture formation and strengthening mechanism in an extruded Mg-Gd-Y-Zn-Zr alloy. Journal of Materials Science & Technology, 2020, 45: 133-145 J]

[6] KimS H, JungJ G, YouB S, et al.. Microstructure and texture variation with Gd addition in extruded magnesium. Journal of Alloys and Compounds, 2017, 695: 344-350 J]

[7] LeiB, JiangB, YangH-b, et al.. Effect of Nd addition on the microstructure and mechanical properties of extruded Mg-Gd-Zr alloy. Materials Science and Engineering A, 2021, 816: 141320 J]

[8] LiB-s, GuanK, YangQ, et al.. Microstructures and mechanical properties of a hot-extruded Mg-8Gd-3Yb-1.2Zn-0.5Zr (wt%) alloy. Journal of Alloys and Compounds, 2019, 776: 666-678 J]

[9] LiJ-l, DongZ-h, YiX, et al.. Twin evolution in cast Mg-Gd-Y alloys and its dependence on aging heat treatment. Journal of Magnesium and Alloys, 2023, 11(7): 2285-2298 J]

[10] LiR G, LiH R, PanH C, et al.. Achieving exceptionally high strength in binary Mg-13Gd alloy by strong texture and substantial precipitates. Scripta Materialia, 2021, 193: 142-146 J]

[11] LiuX, ZhangZ-q, LeQ-c, et al.. Effects of Nd/Gd value on the microstructures and mechanical properties of Mg-Gd-Y-Nd-Zr alloys. Journal of Magnesium and Alloys, 2016, 4(3): 214-219 J]

[12] LvN, ZhaoL-y, YanH, et al.. Texture tailoring and microstructure refinement induced by {112¯1}\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\{11\overline{2}1\}$$\end{document} and {101¯2}\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\{10\overline{1}2\}$$\end{document} twinning in an extruded Mg-Gd alloy. Journal of Alloys and Compounds, 2023, 966: 171590 J]

[13] LyuS-y, XiaoW-l, LiG-d, et al.. Formation mechanism of the abnormal texture during extrusion in Mg-Y-Sm-Zn-Zr alloy. Journal of Alloys and Compounds, 2020, 821: 153477 J]

[14] MeierJ M, CarisJ, LuoA A. Towards high strength cast Mg-RE based alloys: Phase diagrams and strengthening mechanisms. Journal of Magnesium and Alloys, 2022, 10(6): 1401-1427 J]

[15] MouhibF, PeiR, ErolB, et al.. Synergistic effects of solutes on active deformation modes, grain boundary segregation and texture evolution in Mg-Gd-Zn alloys. Materials Science and Engineering A, 2022, 847: 143348 J]

[16] NakataT, KanitaniS, MatsumotoY, et al.. Role of dynamic recrystallization and grain growth on the formation of abnormal basal texture in a high-alloyed Mg-Al-Zn extruded alloy. Materialia, 2023, 27: 101652 J]

[17] Jafari NodooshanH R, LiuW-c, WuG-h, et al.. Effect of Gd content on microstructure and mechanical properties of Mg-Gd-Y-Zr alloys under peak-aged condition. Materials Science and Engineering A, 2014, 615: 79-86 J]

[18] PangH, BaoJ, LiQ-a, et al.. Effect of Sm on microstructures and mechanical properties of Mg-Gd(-Sm)-Zr alloys by hot extrusion and aging treatment. Journal of Materials Research and Technology, 2022, 19: 3877-3893 J]

[19] QinH, YangG-y, KanZ-y, et al.. Effect of substituting Gd with 3 wt% Nd on high temperature creep behaviors of peak-aged Mg-10Gd-0.4Zr casting Mg alloy. Journal of Materials Research and Technology, 2023, 25: 5781-5794 J]

[20] ShiK, LiS-b, YuZ-j, et al.. Microstructure and mechanical performance of Mg-Gd-Y-Nd-Zr alloys prepared via pre-annealing, hot extrusion and ageing. Journal of Alloys and Compounds, 2023, 931: 167476 J]

[21] SongJ-f, ChenJ, XiongX-m, et al.. Research advances of magnesium and magnesium alloys worldwide in 2021. Journal of Magnesium and Alloys, 2022, 10(4): 863-898 J]

[22] WangB-z, TangB, YouC, et al.. Dislocation arrays, precipitate bands and free zones in forged Mg-Gd-Y-Zr alloy. Materials Science and Engineering A, 2020, 775: 138789 J]

[23] WangK, WangJ-f, HuangS, et al.. Formation of an abnormal texture in Mg-Gd-Y-Zn-Mn alloy and its effect on mechanical properties by altering extrusion parameters. Materials Science and Engineering A, 2022, 831: 142270 J]

[24] WangL-h, JalarA, DanL-h. Dynamic precipitation and dynamic recrystallization behaviors of Mg-Gd-Nd-Zr magnesium alloy during thermal compression deformation. Journal of Materials Research and Technology, 2023, 26: 7634-7648 J]

[25] WangL-h, JalarA, DanL-h. Effect of Nd on microstructure and mechanical properties of Mg-7Gd-0.5Zr alloy. Journal of Alloys and Compounds, 2023, 936: 168278 J]

[26] WangQ-d, ChenJ, ZhaoZ, et al.. Microstructure and super high strength of cast Mg-8.5Gd-2.3Y-1.8Ag-0.4Zr alloy. Materials Science and Engineering A, 2010, 528(1): 323-328 J]

[27] WangX-y, YuY, ChenW-z, et al.. Formation mechanism of texture connected with excellent ductility during hot extrusion in Mg-9Gd-5Y-0.5Zr alloy. Materials Science and Engineering A, 2022, 859: 144193 J]

[28] WangX, ZhaoY-x, HuangY-c. Characterization of hot-extruded Mg-Gd-Y-Zn-Zr alloy containing a novel lamellar structure and related high elevated-temperature mechanical properties. Metals and Materials International, 2023, 29(9): 2556-2570 J]

[29] WeiK, XiaoL-r, GaoB, et al.. Effect of aging temperature on the hardening behavior and precipitation evolution of Mg-10Gd alloy. Materials Characterization, 2023, 196: 112580 J]

[30] WeiX-x, JinL, WangF-h, et al.. High strength and ductility Mg-8Gd-3Y-0.5Zr alloy with bimodal structure and nano-precipitates. Journal of Materials Science & Technology, 2020, 44: 19-23 J]

[31] WuG-h, WangC-l, SunM, et al.. Recent developments and applications on high-performance cast magnesium rare-earth alloys. Journal of Magnesium and Alloys, 2021, 9(1): 1-20 J]

[32] XieH, WuG-h, TongX, et al.. The opposite effect of β₁/β″ on the ductility of aged Mg-3Nd-3Gd-0.2Zn-0.5Zr alloy. Journal of Materials Science & Technology, 2023, 149: 67-72 J]

[33] XuC, ZhengM-y, XuS-w, et al.. Improving strength and ductility of Mg-Gd-Y-Zn-Zr alloy simultaneously via extrusion, hot rolling and ageing. Materials Science and Engineering A, 2015, 643: 137-141 J]

[34] XuM-n, LiN, ShaX-c, et al.. In-situ TEM observations on interaction of basal dislocations and β′ phases in a Mg-Gd binary alloy. Materials Science and Engineering A, 2022, 841: 143017 J]

[35] XuW-l, SuC, ChenX-h, et al.. Tailoring precipitates in Mg-12Gd-3Y alloys by Sn addition to obtain superior elevated temperature mechanical properties. Materials Science and Engineering A, 2023, 873: 145006 J]

[36] YangZ, NakataT, XuC, et al.. Preparation of high-performance Mg-Gd-Y-Mn-Sc alloy by heat treatment and extrusion. Journal of Alloys and Compounds, 2023, 934: 167906 J]

[37] YouC, LiuC-m, WanY-c, et al.. Dislocations-induced precipitates and their effect on mechanical properties of Mg-Gd-Y-Zr alloy. Journal of Magnesium and Alloys, 2019, 7(3): 414-418 J]

[38] YouS-h, HuangY-d, KainerK U, et al.. Recent research and developments on wrought magnesium alloys. Journal of Magnesium and Alloys, 2017, 5(3): 239-253 J]

[39] YuH-h, XinY-c, WangM-y, et al.. Hall-petch relationship in Mg alloys: A review. Journal of Materials Science & Technology, 2018, 34(2): 248-256 J]

[40] ZhangJ-h, LiuS-j, WuR-z, et al.. Recent developments in high-strength Mg-RE-based alloys: Focusing on Mg-Gd and Mg-Y systems. Journal of Magnesium and Alloys, 2018, 6(3): 277-291 J]

[41] ZhangM-x, WangZ-x, ZhangZ-m, et al.. Effect of temperature on the microstructure and mechanical properties of Mg-Gd-Y-Zn-Zr alloy during the large height-to-diameter ratio upsetting and extrusion. Journal of Materials Research and Technology, 2023, 26: 8036-8047 J]

[42] ZhangY, WuY-j, PengL-m, et al.. Microstructure evolution and mechanical properties of an ultra-high strength casting Mg-15.6Gd-1.8Ag-0.4Zr alloy. Journal of Alloys and Compounds, 2014, 615: 703-711 J]

[43] ZhangZ-j, YuanL, ShivpuriR, et al.. Achieving high strength and creep resistance of a Mg-13Gd-6Y-0.2Zr alloy forging fabricated by isothermal forging and artificial aging. Materialia, 2023, 27: 101654 J]

[44] ZindalA, JainJ, PrasadR, et al.. Effect of heat treatment variables on the formation of precipitate free zones (PFZs) in Mg-8Al-0.5Zn alloy. Materials Characterization, 2018, 136: 175-182 J]

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