Three-dimensional characterization of intermetallic compound formation in magnesium alloys with micro X-ray computed tomography

Abstract

This comprehensive study investigates the formation and evolution of intermetallic compounds during the solidification process of magnesium alloys using advanced micro X-ray computed tomography. By analyzing both common industrial Mg-Al-Zn alloys and a novel rare earth-containing Mg-Ni-Gd-Y alloy, we aim to characterize the nucleation, growth, and distribution of Al-Mn and eutectic intermetallics across various stages of solidification. The nondestructive imaging technique employed in this research provides high-resolution, three-dimensional insights into the microstructural development, allowing for a detailed examination of the morphology, spatial arrangement, and interconnectivity of intermetallic phases. This approach overcomes limitations of traditional two-dimensional metallographic methods, offering a more comprehensive understanding of the complex three-dimensional structures formed during solidification.

Keywords

magnesium alloy / X-ray computed tomography / solidification / intermetallics / defects

References

[1] Luo A A. Magnesium casting technology for structural applications [J]. Journal of Magnesium and Alloys. 2013, 1(1): 2-22.

[2] Zhu S-m, Easton M A, Abbott T Bet al. . Evaluation of magnesium die-casting alloys for elevated temperature applications: Microstructure, tensile properties, and creep resistance [J]. Metallurgical and Materials Transactions A. 2015, 46(8): 3543-3554.

[3] Dini H, Andersson N E, Jarfors A E W. Effect of Mg₁₇Al₁₂ fraction on mechanical properties of Mg-9%Al-1%Zn cast alloy [J]. Metals. 2016, 6(10): 251.

[4] Zha M, Zhang H-m, Wang Cet al. . Prominent role of a high volume fraction of Mg₁₇Al₁₂ particles on tensile behaviors of rolled Mg-Al-Zn alloys [J]. Journal of Alloys and Compounds. 2017, 728: 682-693.

[5] Zhu T-p, Chen Z W, Gao W. Effect of cooling conditions during casting on fraction of β-Mg₁₇Al₁₂ in Mg-9Al-1Zn cast alloy [J]. Journal of Alloys and Compounds. 2010, 5012291-296.

[6] Gourlay C M, Dahle A K. Dilatant shear bands in solidifying metals [J]. Nature. 2007, 445(7123): 70-73.

[7] Dahle A K, Lee Y C, Nave M Det al. . Development of the as-cast microstructure in magnesium-aluminium alloys [J]. Journal of Light Metals. 2001, 1(1): 61-72.

[8] Dargusch M S, Nave M, Mcdonald S Det al. . The effect of aluminium content on the eutectic morphology of high pressure die cast magnesium-aluminium alloys [J]. Journal of Alloys and Compounds. 2010, 492(12): L64-L68.

[9] Nave M D, Dahle A K, Stjohn D H. The role of zinc in the eutectic solidification of magnesium-aluminium-zinc alloys [M]. Magnesium Technology 2000. 2000243250.

[10] Han G, Liu X-fa. Phase control and formation mechanism of Al-Mn (-Fe) intermetallic particles in Mg-Al-based alloys with FeCl₃ addition or melt superheating [J]. Acta Materialia. 2016, 114: 54-66.

[11] Peng L, Zeng G, Xian Jet al. . Al-Mn-Fe intermetallic formation in AZ91 magnesium alloys: Effects of impurity iron [J]. Intermetallics. 2022, 142: 107465.

[12] Zeng G, Xian J W, Gourlay C M. Nucleation and growth crystallography of Al₈Mn₅ on B2-Al(Mn, Fe) in AZ91 magnesium alloys [J]. Acta Materialia. 2018, 153364-376.

[13] Liu M, Uggowitzer P J, Nagasekhar A Vet al. . Calculated phase diagrams and the corrosion of die-cast Mg-Al alloys [J]. Corrosion Science. 2009, 51(3): 602-619.

[14] Corby C P, Qian M, Ricketts N Jet al. . Investigation of intermetallics in die-casting sludge [C]. Magnesium Technology 2004 Symposium. 2004, Charlotte, North Carolina, USA, The Minerals, Metals & Materials Society209214

[15] Peng L, Zeng G, Su T Cet al. . Al₈Mn₅ particle settling and interactions with oxide films in liquid AZ91 magnesium alloys [J]. JOM. 2019, 71(7): 2235-2244.

[16] Peng L-q, Zeng G, Wang Det al. . Al-Mn intermetallics in high pressure die cast AZ91 and direct chill cast AZ80 [J]. Metals. 2022, 12(2): 266.

[17] Wang Y, Xia M, Fan Zet al. . The effect of Al₈Mn₅ intermetallic particles on grain size of as-cast Mg-Al-Zn AZ91D alloy [J]. Intermetallics. 2010, 1881683-1689.

[18] Liu C-p, Pan F-s, Wang W-qing. Phase analysis of Al-Mn compounds in the AZ magnesium alloys [J]. Materials Science Forum. 2007, 546–549: 395-398.

[19] Pawar S, Zhou X, Hashimoto Tet al. . Investigation of the microstructure and the influence of iron on the formation of Al₈Mn₅ particles in twin roll cast AZ31 magnesium alloy [J]. Journal of Alloys and Compounds. 2015, 628: 195-198.

[20] Zeng G, Shuai S S, Zhu X Zet al. . Al₈Mn₅ in high-pressure die cast AZ91: Twinning, morphology and size distributions [J]. Metallurgical and Materials Transactions A. 2020, 51(5): 2523-2535.

[21] Xian J W, Peng L, Zeng Get al. . Al₁₁Mn₄ formation on Al₈Mn₅ during the solidification and heat treatment of AZ-series magnesium alloys [J]. Materialia. 2021, 19: 101192.

[22] Zeng G, Xian J W, Gourlay C M. Growth of Al₈Mn₅ intermetallic in AZ91 [M]. Magnesium Technology 2017. 2017, Cham, Springer International Publishing85-92.

[23] Zeng G, Zhu X, Ji Set al. . The morphology and distribution of Al₈Mn₅ in high pressure die cast AM50 and AZ91 [M]. Magnesium Technology 2018. 2018, Cham, Springer International Publishing137144.

[24] Tamura Y, Haitani T, Kono N. Liquid solubility of manganese and its influence on grain size of Mg-Al alloys [J]. Materials Transactions. 2006, 47(8): 1968-1974.

[25] Cao P, Qian M, Stjohn D H. Effect of manganese on grain refinement of Mg-Al based alloys [J]. Scripta Materialia. 2006, 54(11): 1853-1858.

[26] Azeem M A, Lee P D, Phillion A Bet al. . Revealing dendritic pattern formation in Ni, Fe and Co alloys using synchrotron tomography [J]. Acta Materialia. 2017, 128: 241-248.

[27] Cai B, Wang J, Kao Aet al. . 4D synchrotron X-ray tomographic quantification of the transition from cellular to dendrite growth during directional solidification [J]. Acta Materialia. 2016, 117: 160-169.

[28] Feng S-k, Liotti E, Grant P S. X-ray imaging of alloy solidification: Crystal formation, growth, instability and defects [J]. Materials. 2022, 15(4): 1319.

[29] Liotti E, Lui A, Connolley Tet al. . Probing interdendritic flow and hot tearing during solidification using real time X-ray imaging and droplet tracking [J]. Acta Materialia. 2022, 240: 118298.

[30] Murphy A G, Mirihanage W U, Browne D Jet al. . Equiaxed dendritic solidification and grain refiner potency characterised through in situ X-radiography [J]. Acta Materialia. 2015, 9583-89.

[31] Shuai S-s, Guo E-y, Phillion A Bet al. . Fast synchrotron X-ray tomographic quantification of dendrite evolution during the solidification of MgSn alloys [J]. Acta Materialia. 2016, 118: 260-269.

[32] Song Z-h, Magdysyuk O V, Tang Let al. . Growth dynamics of faceted Al₁₃Fe₄ intermetallic revealed by high-speed synchrotron X-ray quantification [J]. Journal of Alloys and Compounds. 2021, 861: 158604.

[33] Terzi S, Taylor J A, Cho Y Het al. . In situ study of nucleation and growth of the irregular α-Al/β-Al₅FeSi eutectic by 3-D synchrotron X-ray microtomography [J]. Acta Materialia. 2010, 58165370-5380.

[34] Wang M Y, Williams J J, Jiang Let al. . Dendritic morphology of α-Mg during the solidification of Mg-based alloys: 3D experimental characterization by X-ray synchrotron tomography and phase-field simulations [J]. Scripta Materialia. 2011, 6510855-858.

[35] Yasuda H, Hashimoto T, Sei Net al. . Investigation using 4D-CT of massive-like transformation from the δ to γ phase during and after δ-solidification in carbon steels [J]. IOP Conference Series: Materials Science and Engineering. 2019, 529(1): 012013.

[36] Yasuda H, Nagira T, Yoshiya Met al. . In-situ observation of peritectic solidification in Sn-Cd and Fe-C alloys [J]. IOP Conference Series: Materials Science and Engineering. 2012, 271012084.

[37] Gourlay C M, Nogita K, Dahle A Ket al. . In situ investigation of unidirectional solidification in Sn-0.7Cu and Sn-0.7Cu-0.06Ni [J]. Acta Materialia. 2011, 59104043-4054.

[38] Salleh M A A M, Gourlay C M, Xian J Wet al. . In situ imaging of microstructure formation in electronic interconnections [J]. Scientific Reports. 2017, 7: 40010.

[39] Xian J W, Belyakov S A, Ollivier Met al. . Cu₆Sn₅ crystal growth mechanisms during solidification of electronic interconnections [J]. Acta Materialia. 2017, 126540-551.

[40] Zeng G, Callaghan M D, Mcdonald S Det al. . In situ studies revealing dendrite and eutectic growth during the solidification of Sn-0.7Cu-0.5Ag Pb-free solder alloy [J]. Journal of Alloys and Compounds. 2019, 797: 804-810.

[41] Zeng G, Mcdonald S D, Gourlay C Met al. . Solidification of Sn-0.7Cu-0.15Zn solder: In situ observation [J]. Metallurgical and Materials Transactions A. 2014, 45(2): 918-926.

[42] Casari D, Mirihanage W U, Falch K Vet al. . α-Mg primary phase formation and dendritic morphology transition in solidification of a Mg-Nd-Gd-Zn-Zr casting alloy [J]. Acta Materialia. 2016, 116: 177-187.

[43] Shuai S-s, Guo E-y, Wang Jet al. . Synchrotron tomographic quantification of the influence of Zn concentration on dendritic growth in Mg-Zn alloys [J]. Acta Materialia. 2018, 156: 287-296.

[44] Zeng G, Nogita K, Belyakov Set al. . Real-time observation of AZ91 solidification by synchrotron radiography [M]. Magnesium Technology 2017. 2017, Cham, Springer International Publishing597603.

[45] Yang Y, Deng Y-c, Zhang R-fet al. . Influence of β-Mg₁₇Al₁₂ and Al-Mn intermetallic compounds on the corrosion behaviour of cast and solution treated Mg-Al-Zn-Mn alloys [J]. Corrosion Science. 2023, 222: 111363.

[46] Deng Y-c, Sun W, Yang Yet al. . Effects of Mg₂Sn precipitation on the age-hardening and deformation behaviour of a Mg-Sn-Al-Zn alloy [J]. Materials Science and Engineering A. 2023, 867144714.

[47] Gulliver G H. The quantitative effect of rapid cooling upon the constitution of binary alloys [J]. J Inst Met. 1913, 9(1): 120-157

[48] Kundin J, Wang P, Emmerich Het al. . Investigation of Al-Cu-Ni alloy solidification: Thermodynamics, experiments and phase-field modeling [J]. The European Physical Journal Special Topics. 2014, 2233567-590.

[49] Han M-x, Zhu X-z, Gao Tet al. . Revealing the roles of Al₄C₃ and Al₈Mn₅ during α-Mg nucleation in Mg-Al based alloys [J]. Journal of Alloys and Compounds. 2017, 705: 14-21.

[50] Sarvesha R, Ghori U U R, Thirunavukkarasu Get al. . A study on the phase transformation of γ₂-Al₈Mn₅ to LT-Al₁₁Mn₄ during solutionizing in AZ91 alloy [J]. Journal of Alloys and Compounds. 2021, 873: 159836.

[51] Wang D, Peng L-q, Gourlay C M. Al-Mn-based decagonal quasicrystal in AZ magnesium alloys and its nucleation on Al₈Mn₅ during solidification [J]. Scripta Materialia. 2024, 241115886.

[52] Deng Y-c, Zeng G, Xian J-wet al. . Eutectic intermetallic formation during solidification of a Mg-Sn-Al-Zn-Mn alloy [J]. Materials Characterization. 2022, 186111807.

[53] Monas A, Shchyglo O, Kim S Jet al. . Divorced eutectic solidification of Mg-Al alloys [J]. JOM. 2015, 67(8): 1805-1811.

[54] Barbagallo S, Laukli H I, Lohne Oet al. . Divorced eutectic in a HPDC magnesium-aluminum alloy [J]. Journal of Alloys and Compounds. 2004, 37812226-232.

[55] Du G, Liu F, Li J-bing. Evolution of microstructures and divorced eutectic TiC formed during solidification of the wear-resistant steel [J]. Materials Letters. 2020, 265: 127406.

[56] Verhoeven J D, Gibson E D. The divorced eutectoid transformation in steel [J]. Metallurgical and Materials Transactions A. 1998, 29(4): 1181-1189.

[57] Wu M-w, Xiong S-mei. Microstructure characteristics of the eutectics of die cast AM60B magnesium alloy [J]. Journal of Materials Science & Technology. 2011, 27121150-1156.

[58] Wu M-w, Hua L, Xiong S-mei. Modeling studies on divorced eutectic formation of high pressure die cast magnesium alloy [J]. China Foundry. 2018, 15(1): 58-65.

[59] Xia Y-j, Li J, Fan D-det al. . The effect of aluminum on the divorced eutectic transformation of MnS inclusions [J]. Metallurgical and Materials Transactions B. 2021, 52(2): 1118-1131.

[60] Zhu M-f, Zhang L, Zhao H-let al. . Modeling of microstructural evolution during divorced eutectic solidification of spheroidal graphite irons [J]. Acta Materialia. 2015, 84: 413-425.

[61] Kadali K, Dubey D, Sarvesha Ret al. . Dissolution kinetics of Mg₁₇Al₁₂ eutectic phase and its effect on corrosion behavior of As-cast AZ80 magnesium alloy [J]. JOM. 2019, 71(7): 2209-2218.

[62] Korgiopoulos K, Langelier B, Pekguleryuz M. Mg₁₇Al₁₂ phase refinement and the improved mechanical performance of Mg-6Al alloy with trace erbium addition [J]. Materials Science and Engineering A. 2021, 812: 141075.

[63] Lin C J, Peng L, Xian J Wet al. . Eutectic solidification in Mg-9Al-0.7Zn: From divorced to coupled growth [J]. Journal of Alloys and Compounds. 2023, 938168571.

[64] Lunder O, Lein J E, Aune T Ket al. . The role of Mg₁₇Al₁₂ phase in the corrosion of Mg alloy AZ91 [J]. Corrosion. 1989, 45(9): 741-748.

[65] Weiler J P. The role of the Mg₁₇Al₁₂-phase in the high-pressure die-cast magnesium-aluminum alloy system [J]. Journal of Magnesium and Alloys. 2023, 11114235-4246.

[66] Yao H, Tan X F, Sun Wet al. . Fast activation of Na micro-alloyed Mg-Ni-Gd-Y-Zn-Cu alloys for solid-state hydrogen storage [J]. International Journal of Hydrogen Energy. 2025, 118: 237-250.

[67] Han G, Liu X-fa. Phase control and formation mechanism of Al-Mn (-Fe) intermetallic particles in Mg-Albased alloys with FeCl₃ addition or melt superheating [J]. Acta Materialia. 2016, 114: 54-66.

[68] Cai H-s, Zhang N-n, Liu Let al. . Effects of cooling rate on the microstructure and properties of magnesium alloy-a review [J]. Journal of Magnesium and Alloys. 2024, 12(8): 3094-3114.

[69] Nave MD, Dahle AK, Stjohn DH. Eutectic growth morphologies in magnesium-aluminium alloys [C]. Magnesium Technology 2000 Symposium. 2000, Nashville, Tennessee, USA, The Minerals, Metals & Materials Society233242.

[70] Chaijaruwanich A, Lee P D, Dashwood R Jet al. . Evolution of pore morphology and distribution during the homogenization of direct chill cast Al - Mg alloys [J]. Acta Materialia. 2007, 55(1): 285-293.

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