Mg-Sn共晶合金的凝固组织演化及晶体生长机理

唐玲; 刘文义; 王永善

doi:10.11868/j.issn.1005-5053.2022.000149

Mg-Sn共晶合金的凝固组织演化及晶体生长机理

doi: 10.11868/j.issn.1005-5053.2022.000149

陕西理工大学材料科学与工程学院，陕西汉中 723003

基金项目: 陕西省科技厅科研基金项目（2020JM-599）

详细信息

通讯作者:
唐玲（1979—），女，硕士，教授，主要从事凝固理论与新材料制备等方面的研究，联系地址：陕西省汉中市汉台区陕西理工大学（ 723000），E-mail：snuttang@163.com

中图分类号: TG146.22
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- PDF下载量: 10
- 被引次数: 0
出版历程
- 收稿日期: 2022-09-14
- 录用日期: 2023-08-08
- 修回日期: 2023-06-18
- 网络出版日期: 2023-10-18
- 刊出日期: 2023-10-01

Solidification structure evolution and crystal growth mechanism of Mg-Sn eutectic alloy

School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong723003, Shaanxi，China

摘要

摘要: 采用金相显微镜（OM）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）和能谱仪（EDS），研究自由凝固下Mg-Sn共晶合金在不同凝固阶段的组织、相的生长形态及相组成等。探讨Mg-Sn共晶合金的晶体生长机制以及冷却速度对合金显微组织的影响。结果表明：Mg-Sn亚共晶合金中的凝固组织为六角蔷薇花状的初生α-Mg相和共晶Mg/Mg₂Sn层片组织的混合结构；Mg-Sn过共晶合金中的凝固组织为棱角分明的初生Mg₂Sn金属间化合物相和共晶Mg/Mg₂Sn层片组织的混合结构；在亚共晶成分范围内，随着Sn含量的增加，初生α-Mg相含量减少，共晶相含量增多；随着冷却速率的提高，合金组织得到了明显的细化；初生α-Mg相为非小平面相，初生Mg₂Sn金属间化合物相为小平面相。
- 亚共晶 /
- 共晶自生复合材料 /
- 非小平面相 /
- 小平面相
Abstract: Optical microscope, X-ray diffractometer, scanning electron microscope and energy dispersive spectrometer were used to study the microstructure, phase growth morphology and phase composition of free solidified Mg-Sn eutectic in-situ composites at different solidification stages.The crystal growth mechanism of Mg-Sn eutectic in-situ composite and the effect of cooling rate on the microstructure of the alloy were investigated.The results show that the solidification structure of Mg-Sn hypoeutectic alloy is hexagonal rose-like primary α-Mg phase and eutectic Mg/Mg₂Sn lamellar mixed structure. The solidification structure of Mg-Sn hypereutectic alloy is a mixed structure of angular primary Mg₂Sn intermetallic compound phase and eutectic Mg/Mg₂Sn lamellar structure.With the increase of Sn content, the quantity of primary α-Mg phase decreased and the content of eutectic phase increased. With the increase of cooling rate, the microstructure of the alloy is obviously refined.The α-Mg primary phase is a non-faceted phase, and the primary Mg₂Sn intermetallic compound phase is a faceted phase.
- hypoeutectic alloy /
- eutectic in-situ composites /
- faceted phase /
- non-faceted phase

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图 1 实验所需的金属模具示意图　（a）金属阶梯模具示意图；（b）金属圆柱形模具

Figure 1. Metal mold map required for experiment　（a） schematic diagram of metal step mold；（b） metal cylindrical mold

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图 2 Mg-Sn合金的XRD图

Figure 2. XRD patterns of as-cast Mg-Sn alloys

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图 3 Mg-35%Sn合金在不同阶梯处的微观形貌　（a）厚壁处；（b）中壁处；（c）薄壁处；（d）图（c）局部放大图

Figure 3. Solidification microstructure of Mg-35% Sn alloy at different steps　（a） thick wall；（b） middle wall;（c） thin wall；（d） partial enlarged picture of Fig.（c）

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图 4 Mg-35%Sn合金能谱面扫描分析图　（a）整体照片；（b）镁元素分布图；（c）锡元素分布图

Figure 4. Energy spectrum scanning analysis diagram of Mg-35%Sn alloy　（a）SEM；（b） Mg element distribution map；（c） Sn element distribution map

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图 5 Mg-40%Sn合金在不同阶梯处的微观形貌　（a）厚壁处；（b）中壁处；（c）薄壁处；（d）图（c）局部放大图

Figure 5. Solidification microstructures of Mg-40% Sn alloy at different steps　（a） thick wall；（b）middle wall；（c） thin wall；（d） partial enlarged picture of Fig.（c）

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图 6 Mg-50%Sn合金在不同阶梯处的微观形貌　（a）厚壁处；（b）中壁处；（c）薄壁处；（d）图（c）局部放大图

Figure 6. Solidification microstructures of Mg-50% Sn alloy at different steps　（a）thick wall；（b）middle wall；（c） thin wall；（d） partial enlarged picture of Fig.（c）

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图 7 Mg-50%Sn合金能谱面扫描分析图　（a）整体照片；（b）Mg元素分布图；（c）Sn元素分布图

Figure 7. Energy spectrum scanning analysis diagram of Mg-35%Sn alloy　（a）SEM；（b）Mg element distribution map；（c） Sn element distribution map

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图 8 Mg-35%Sn合金圆柱形试样横截面金相组织图

Figure 8. Cross sectional microstructure of Mg-35%Sn alloy cylindrical specimen

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图 9 Mg-Sn合金两种不同初生相的生长形貌图　（a）初生α-Mg相；（b）初生Mg₂Sn金属相化合物相

Figure 9. Growth morphologies of two different primary phases in Mg-Sn alloy　（a） primary phase of α-Mg；（b） primary phase of Mg₂Sn intermetallic compound

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表 1 热物理化学参数^[21]

Table 1. Thermophysical and chemical parameters^[21]

Substance	State	$ {C}_{\mathrm{p}}=a+bT+c{T}^{-2}/ (\mathrm{J}\text{•} {\mathrm{k}\mathrm{g}}^{-1}\text{•} {\mathrm{K}}^{-1}) $			T_m/K	T_E/K	p+q
Substance	State	a	b	c	T_m/K	T_E/K	p+q
Mg₂Sn	Solid	460	0.0124	–200000	1056	836	3
Mg₂Sn	Liquid	270	0	0	1056	836	3

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