Experimental and Simulation Investigation of Nd Additions on As-Cast Microstructure and Precipitate Development in Mg–Nd System Alloys |
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Authors: | Xuewei Yan Bin Su Xuemei Yang Qingdong Xu Xiaopeng Zhang Jing Wang Zhenhua Wen |
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Affiliation: | 1.School of Aero Engine, Zhengzhou University of Aeronautics, Zhengzhou 450046, China;2.Institute of Materials, China Academy of Engineering Physics, Jiangyou 621700, China; (Q.X.); (X.Z.); (J.W.);3.School of Aerospace Engineering, Zhengzhou University of Aeronautics, Zhengzhou 450046, China; |
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Abstract: | The microstructure and precipitate evolution of as-cast Mg–Nd alloys with different contents of Nd was investigated via experimental and simulation methods. The research showed that the as-cast microstructure of Mg–Nd alloy consisted of α-Mg dendrites and the intermetallic phases. A metastable β phase precipitated, followed by α-Mg dendrites that could be confirmed as Mg12Nd by X-ray diffraction (XRD) analysis. The amount of β-Mg12Nd presented a rising trend with increasing Nd additions. In addition, the tertiary phase was also observed in as-cast Mg–Nd alloy when Nd content was greater than 3 wt.%, which precipitated from the oversaturated α-Mg matrix. The tertiary phase should be β1-Mg3Nd, which is also a metastable phase with a face-centered cubic lattice. However, it is a pity that the tertiary phase was not detected by the XRD technique. Moreover, an effective cellular automaton (CA) model was explored and applied to simulate the time-dependent α-Mg/β1-Mg3Nd eutectic growth. The simulated results of α-Mg/β1-Mg3Nd eutectic growth in Mg-3Nd presented that the growth of α-Mg dendrites was accompanied by the nucleation and growth of β1-Mg3Nd precipitates and eventually formed a eutectic structure. The eutectic morphologies for Mg–Nd system alloys with different Nd contents were also simulated using the proposed model, and the results revealed that α-Mg dendrite was a refinement, and the amount of α-Mg/β1-Mg3Nd eutectic was promoted, with increasing Nd content. |
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Keywords: | Mg– Nd alloy, microstructure, precipitate, eutectic growth, modelling and simulation |
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