Effect of the Mg₃N₂ Sub-Micron Particle on the Grain Refinement of AZ80 Alloy

Abstract:

AZ80 alloy has been widely used to produce high performance Mg casting and wrought parts for high-end applications due to its high mechanical properties and deformation ability. However, at least two important issues still need to be solved in order to further improve its mechanical properties and deformation ability. Firstly, the grain size of α-Mg in AZ80 alloy is relatively large (more than 1000 µm) due to a lack of efficient grain refinement methodologies. Secondly, the size of the eutectic Mg₁₇Al₁₂ phase is also large and the distribution of the eutectic Mg₁₇Al₁₂ phase is continuous, which is very harmful for the mechanical properties, in particular to elongation. In this paper, these two important issues are investigated by adding Mg₃N₂ sub-micron particle into AZ80 alloy and thereby refining the α-Mg and the eutectic Mg₁₇Al₁₂ phase. Firstly, the Mg₃N₂ sub-micron particle was directly added into AZ80 alloy by using mechanically stirring in the semi-solid state, subsequently the melting temperature was increased above the liquidous temperature, and finally the melting was casted in the liquid state. It was found that the grain size of α-Mg can be refined from 883.8 µm to 169.9 µm. More importantly, the eutectic Mg₁₇Al₁₂ phase was also refined and the distribution became discontinuous. It should be noted that directly adding the Mg₃N₂ sub-micron particle into AZ80 alloy leads to a great loss of the Mg₃N₂ sub-micron particle due to the weak wetting behavior between the Mg₃N₂ sub-micron particle and Mg melt. The second methodology through mixing Mg₃N₂ sub-micron particles with AZ91 chips using a twin extruder was also used to prepare AZ91 master alloy with 3wt.% Mg₃N₂ sub-micron particle, which was subsequently added into AZ80 alloy in the liquid state. In this way, a significant grain refinement of α-Mg and a simultaneous refinement of the eutectic Mg₁₇Al₁₂ phase in AZ80 alloy was also achieved. The grain size of α-Mg can be refined from 883.8 µm to 325.9 µm. However, no significant grain refinement by using UST was observed. Instead, the grain size increases from 325.9 µm to 448.6 µm, indicating that the Mg₃N₂ sub-micron particle may lose its grain refinement potency due to possible aggregation and clustering. This paper provides an efficient and simple methodology for the grain refinement of α-Mg and the simultaneous refinement of the eutectic Mg₁₇Al₁₂ phase in AZ80 alloy.

• Periodical: Solid State Phenomena (Volume 327)
• Pages: 45-53
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.327.45
• Online since: January 2022
• Authors: Jie Hua Li*, Maria Pammer, Ernst Neunteufl, Peter Schumacher
• Keywords: AZ80 Alloy, Eutectic Mg₁₇Al₁₂, Grain Refinement, Mg₃N₂ Nanoparticle, Semi-Solid Casting

References

[1] D.H. StHohn, M. Qian, M.A. Easton, P. Cao, Z. Hildebrand, Grain refinement of Magnesium Alloys, Metallurgical and Materials Transactions A, 36 (2005) 1669-1679.

DOI: 10.1007/s11661-005-0030-6

[2] G. Klösch, P. Schumacher, B.J. McKay, Preliminary investigation on the grain refinement behavior of ZrB particles in Mg-Al alloys, in A.A. Luo, , N.R. Neelameggham, and R.S. Beals, (eds.) MINERALS, METALS & MATERIALS SOC., (2006) 69 - 75.

DOI: 10.1002/9781118859803.ch42

[3] K. Korgiopoulos, B. Langelier, M. Pekguleryuz, Mg17Al12 phase refinement and the improved mechanical performance of Mg–6Al alloy with trace erbium addition, Materials Science & Engineering A 812 (2021) 141075.

DOI: 10.1016/j.msea.2021.141075

[4] H.Z Ye, X.Y. Liu, B. Luan, In situ synthesis of AlN particles in Mg–Al alloy by Mg3N2 addition, Materials letters, 58 (2004) 1361-2364.

DOI: 10.1016/j.matlet.2004.02.028

[5] M. Kobashi, N. Okayama, T. Choh, Synthesis of AlN/Al Alloy Composites by in situ Reaction between Mg3N2 and Aluminum, Materials Transactions, 38 (1997) 260-265.

DOI: 10.2320/matertrans1989.38.260

[6] H.Z. Ye, X.Y. liu, B. Luan, In situ synthesis of AlN in Mg–Al alloys by liquid nitridation, Journal of Materials Processing Technology, 166 (2005) 79-85.

DOI: 10.1016/j.jmatprotec.2004.06.033

[7] C. Yang, H. Lü, G. Chen, F. Liu, In Situ Synthesis and Formation Mechanism of AlN in Mg-Al Alloys, Rare Metal Materials and Engineering, 45 (2016) 0018-0022.

[8] Z. Li, T. Gao, Q. Xu, H. Yang, M. Han, X. Liu, Microstructure and Mechanical Properties of an AlN/Mg–Al Composite Synthesized by Al–AlN Master Alloy, International Journal of Metalcasting, 13 (2019) 384-391.

DOI: 10.1007/s40962-018-0261-0

[9] T. Gao, Z. Li, K. Hu, Y. Bian, X. Liu, Assessment of AlN/Mg–8Al Composites Reinforced with In Situ and/or Ex Situ AlN Particles, Materials, 14 (2021) https://doi.org/10.3390/ma14010052.

DOI: 10.3390/ma14010052

[10] H.M. Fu, M.X. Zhang, D. Qiu, P.M. Kelly, J.A. Taylor, Grain refinement by AlN particles in Mg–Al based alloys, Journal of Alloys and Compounds, 478 (2009) 809-812.

DOI: 10.1016/j.jallcom.2008.12.029

[11] D. Giannopoulou, H. Dieringa, J. Bohlen, Influence of AlN Nanoparticle Addition on Microstructure and Mechanical Properties of Extruded Pure Magnesium and an Aluminum-Free Mg-Zn-Y Alloy, Metal, 9 (2019) 667, doi:3390/met9060667.

DOI: 10.3390/met9060667

[12] S. Vorozhtsov, A. Khrustalyov, M. Khmeleva, I. Zhukov, Structure and deformation characteristics in magnesium alloy ZK51A reinforced with AlN nanoparticles, AIP conference proceeding 1772 (2016) 030004 https://doi.org/10.1063/1.4964542.

DOI: 10.1063/1.4964542

[13] H. Yang, D. Zander, Y. Huang, K. Kainer, H. Dieringa, Individual/synergistic effects of Al and AlN on the microstructural evolution and creep resistance of Elektron21 alloy, Materials Science & Engineering A 777 (2020) 139072.

DOI: 10.1016/j.msea.2020.139072

[14] M. Garrido, L. Davoust, R. Daudin, L. Salvo, W. Sillekens, Y. Fautrelle. Reinforcement of magnesium Elektron 21 with aluminium nitride (AlN) nanoparticles dispersed using a travelling magnetic field, Metall. Res. Technol. 203 (2020) 107-117.

DOI: 10.1051/metal/2020016

[15] G. Cao, H. Choi, J. Oportus, H. Konishi, X. Li, Study on tensile properties and microstructure of cast AZ91D/AlN nanocomposites, Materials Science and Engineering: A, 494 (2008) 127-131.

DOI: 10.1016/j.msea.2008.04.070

[16] W. Qiu, Z. Liu, R. Yu, J. Chen, Y. Ren, J. He, W. Li, C. Li, Utilization of VN particles for grain refinement and mechanical properties of AZ31 magnesium alloy, Journal of Alloys and Compounds, 781 (2019) 1150-1158.

DOI: 10.1016/j.jallcom.2018.12.124

[17] A.l. Greer, Overview: Application of heterogeneous nucleation in grain-refining of metals, J. Chem. Phys. 145 (2016) 211704 https://doi.org/10.1063/1.4968846.

DOI: 10.1063/1.4968846

[18] E. Guo, S. Shuai, D. Kazantsev, S. Karagadde, A. Phillion, T. Jing, W. Li, P. Lee, The influence of nanoparticles on dendritic grain growth in Mg alloys, Acta Materialia, 152 (2018) 127-137.

DOI: 10.1016/j.actamat.2018.04.023

[19] L. Chen, J. Xu, H. Choi, M. Pozuelo, X. Ma, S. Bhowmick, J. Yang, S. Mathaudhu, X. Li, Processing and properties of magnesium containing a dense uniform dispersion of nanoparticles, Nature, 528 (2015) 539-543.

DOI: 10.1038/nature16445

[20] L. Chen, J. Xu, H. Choi, H. Konishi, S. Jin, X. Li, Rapid control of phase growth by nanoparticles, Nature communications, 5 (2014) 1-9.

[21] K. Nie, Y. Guo, P. Munroe, K. Deng, X. Kang, Microstructure and tensile properties of magnesium matrix nanocomposite reinforced by high mass fraction of nano-sized particles including TiC and MgZn2, Journal of Alloys and Compounds, 819 (2020) 153348.

DOI: 10.1016/j.jallcom.2019.153348

[22] T. Davis, L. Bichler, F. D´Elia, N. Hort, Effect of TiBor on the grain refinement and hot tearing susceptibility of AZ91D magnesium alloy, Journal of Alloys and Compounds, 759 (2018) 70-79.

DOI: 10.1016/j.jallcom.2018.05.129