Microstructural evaluation and mechanical properties of semi-solid cast AZ91 and AZ91-1%Ca magnesium alloy through rotating container process

IF 7.9 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A Pub Date : 2026-03-01 Epub Date: 2026-02-10 DOI:10.1016/j.msea.2026.149896

E. Ghaniabadi, S.G. Shabestari, E. Heidari

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引用次数: 0

Abstract

The semi-solid rheocast method along with the applying shear stress has been used to create a non-dendritic morphology of AZ91 alloy. By performing thermal analysis during the semi-solid process, the relationship between temperature, shear stress, and solid fraction was determined. The metallographic results confirmed the creation of a non-dendritic microstructure with container rotation speeds of 180 RPM and 210 RPM. The mechanism behind the formation of the non-dendritic morphology involved the generation of an effective displacement fluid flow, which increased the number of the nuclei. This, in turn, facilitated multidirectional growth of the initial dendrites, reduced thermal and concentration gradients, and re-melted the roots of the secondary dendrite arms.

The highest sphericity of non-dendritic grains (0.72), along with the greatest surface density and smallest grain size, was achieved by applying shear stress to the semi-solid mixture at a speed of 180 RPM, up to a temperature of 585 °C. Under the same conditions, the compressive ultimate strength, yield strength, and toughness of the impact test have increased by 25%, 33%, and 49%, respectively. Adding 1% calcium to AZ91 has increased the ultimate strength, yield, and impact toughness by 26%, 57%, and 48%, respectively. By incorporating 1% calcium while applying the semi-solid process under optimal conditions, the ultimate strength, yield strength, and toughness increased by 50%, 88%, and 85%, respectively. A significant finding of this research is the simultaneous enhancement of strength and ductility, resulting in a substantial increase in toughness. In fact, when the rotating container process (RCP) was applied under optimal conditions to both the AZ91 and AZ91-1Ca alloys, the samples exhibited an energy absorption that was 49% and 85% higher, respectively, than that of fractured samples subjected to impact loads.

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旋转容器法半固态铸造AZ91及AZ91-1% ca镁合金的显微组织及力学性能评价

采用半固态流变铸造法和施加剪切应力的方法制备了AZ91合金的非枝晶形貌。通过对半固态过程进行热分析，确定了温度、剪切应力和固相含量之间的关系。金相结果证实，当容器转速为180转/分和210转/分时，形成了非枝晶组织。非枝晶形态形成背后的机制涉及有效置换流体流动的产生，这增加了核的数量。这反过来又促进了初始枝晶的多向生长，降低了热梯度和浓度梯度，并重新熔化了次级枝晶臂的根部。在转速为180转/分、温度为585℃的条件下，对半固态混合物施加剪切应力，获得了最高的非枝晶晶粒球形度（0.72）、最大的表面密度和最小的晶粒尺寸。在相同条件下，冲击试验的抗压极限强度、屈服强度和韧性分别提高了25%、33%和49%。在AZ91中添加1%的钙，AZ91的极限强度、屈服和冲击韧性分别提高了26%、57%和48%。在最佳条件下，在半固态工艺中加入1%的钙，合金的极限强度、屈服强度和韧性分别提高了50%、88%和85%。本研究的一个重要发现是强度和延性的同时增强，从而导致韧性的大幅增加。事实上，当旋转容器工艺（RCP）在最佳条件下应用于AZ91和AZ91- 1ca合金时，样品的能量吸收分别比受冲击载荷作用的断裂样品高49%和85%。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Materials Science and Engineering: A 工程技术-材料科学：综合

CiteScore

11.50

自引率

15.60%

发文量

1811

审稿时长

31 days

期刊介绍： Materials Science and Engineering A provides an international medium for the publication of theoretical and experimental studies related to the load-bearing capacity of materials as influenced by their basic properties, processing history, microstructure and operating environment. Appropriate submissions to Materials Science and Engineering A should include scientific and/or engineering factors which affect the microstructure - strength relationships of materials and report the changes to mechanical behavior.