Key Takeaways & Executive Findings
- •• Combined pre-compression and pre-aging yields the most refined and densest precipitate distribution, resulting in superior age-hardening performance in Mg-9.8Sn-3.0Zn alloy. • Pre-aging alone enhances the number density of precipitates compared to direct aging, attributed to MgZn2 phases acting as heterogeneous nucleation sites for Mg2Sn. • The synergistic effect of pre-compression-induced lattice defects and pre-aging-formed Mg3Sn/MgZn2 phases maximizes heterogeneous nucleation sites, leading to the highest precipitate density. • The study provides a cost-effective strategy to improve the age-hardening response of Mg-Sn-Zn alloys, which is significant for lightweight high-strength applications.
Abstract
The effects of pre-compression and pre-aging on the age-hardening response and microstructure of Mg-9.8Sn-3.0Zn (wt.%) alloy have been investigated via hardness test and advanced electron microscopy. The alloy subjected to both pre-compression and pre-aging exhibits the most refined and densest distribution of precipitates upon aging at 200 ℃, leading to the superior age-hardening performance observed in the alloy. Comparatively, the alloy that underwent only pre-aging displayed a greater number density of precipitates than its counterpart that was neither pre-compressed nor pre-aged when both were aged to their peak conditions at 200 ℃, indicating an enhanced age-hardening response in the pre-aged alloy. The precipitates in these three peak-aged alloys consist of Mg2Sn and MgZn2 phases. The reason why the pre-aged alloy has a higher number density of precipitates than the directly aged alloy is that MgZn2 phase formed during pre-aging can serve as heterogeneous nucleation site for the formation of Mg2Sn. The reason why the pre-compression and pre-aged alloy has the highest number density of precipitates is that Mg3Sn and MgZn2 phases formed during pre-aging, alongside lattice defects introduced during pre-compression, collectively act as effective heterogeneous nucleation sites for the formation of Mg2Sn during the subsequent aging at 200 ℃.
1. Introduction
The regulation of precipitates characteristics to enhance the strengthening effect of lightweight high-strength Mg alloys is a significant research focus in the field of metal structural materials [1−4]. Mg-Sn alloys have gained widespread attention in recent years due to their cost-effectiveness, absence of rare earth elements, and high volume fraction of precipitates during aging [5, 6]. The precipitates in Mg-Sn alloys include Guinier-Preston GP zone, β'-Mg3Sn and β-Mg2Sn phases [7, 8]. Mg2Sn phase is the primary strengthening and stable phase [9−11]. The Mg3Sn phase is a metastable phase that forms during low temperature aging, serving as the heterogeneous nucleation site for the precipitation of β phase in the subsequent aging at high temperature [7]. The age-hardening response of Mg-Sn alloy is reported to have a sluggish rate, typically requiring over 300 h to reach its peak hardness, accompanied with only a moderate increase of 10HV in hardness [12]. The undesirable precipitation strengthening of the Mg-Sn binary alloy is attributed to the formation of the basal Mg2Sn precipitate with a coarse size and a sparse distribution [13].
The incorporation of alloying elements can refine the Mg2Sn precipitate in the Mg-Sn binary alloy [14], or alter the type of secondary phase [14], or generate a novel precipitate phase [15], and then enhance the mechanical properties of the alloy to some extent. It has been reported that the addition of Zn can significantly enhance and expedite the age-hardening reaction of Mg-Sn binary alloys [16, 17]. SASAKI et al [18] reported that the inclusion of Zn can refine the Mg2Sn precipitate, and lead to the formation of non-basal Mg2Sn precipitates, consequently enhancing the age-hardening effect. It is proposed that Zn has two different roles in the Mg-Sn alloys: When Zn content is minor, Zn always segregates to the interphase boundaries between Mg2Sn and Mg matrix, decreasing the interfacial energy of Mg2Sn and increasing its nucleation rate [19]; When Zn content is major, Zn-containing precipitate forms during aging [18]. Although addition of Zn can enhance the age-hardening response, the peak hardness of the Mg-Sn-Zn alloys is still less than 72.5HV [20].
It was reported that pre-aging or pre-compression is an effective strategy to improve the age-hardening response of the age-hardenable alloy [21−23]. For the role of pre-aging, a multitude of dispersed small GP zones and metastable phases are generated in the initial stage of low temperature, and these metastable phases may act as heterogeneous nucleation sites for the formation of strengthening ph
Loading authentic research manuscript (Pages 1–5)...
LIU Yun, LIU Chao-qiang, NI Song, SONG Min (2025). Influence of pre-compression and pre-aging on precipitation behavior in casting Mg-9.8Sn-3.0Zn alloy. Journal of Central South University. https://doi.org/10.1007/s11771-025-6041-0
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the effect of pre-compression and pre-aging on the age-hardening response of Mg-9.8Sn-3.0Zn alloy?
The combination of pre-compression and pre-aging results in the most refined and densest precipitate distribution, leading to superior age-hardening performance. Pre-aging alone also enhances the number density of precipitates compared to direct aging.
What are the precipitates formed in the peak-aged Mg-9.8Sn-3.0Zn alloy?
The precipitates in the peak-aged alloy consist of Mg2Sn and MgZn2 phases.
Why does pre-aging improve the number density of precipitates?
Pre-aging forms MgZn2 phases that act as heterogeneous nucleation sites for the formation of Mg2Sn during subsequent aging, thereby increasing the number density of precipitates.
Why does the combined pre-compression and pre-aging yield the highest precipitate density?
The combination introduces lattice defects from pre-compression and forms Mg3Sn and MgZn2 phases during pre-aging, which collectively serve as effective heterogeneous nucleation sites for Mg2Sn precipitation.
What is the significance of this study for Mg alloy applications?
The study provides a cost-effective strategy to enhance the age-hardening response of Mg-Sn-Zn alloys, which is important for developing lightweight high-strength materials for structural applications.
Related Technical Papers & Translations
Design and optimization of a high-efficiency distillation process for cellulosic fuel ethanol integrated with thermal coupling and molecular sieve adsorption
To address the challenges of high energy consumption and prominent costs in the traditional three-columns distillation process for cellulosic fuel ethanol, a distillation—molecular sieve coupling separation process is proposed. This process integrates a three-column (crude distillation column, first distillation column, second distillation column) system with a 3A molecular sieve adsorption deep dehydration unit. A thermal coupling network is constructed via differential pressure design (steam from medium/high-pressure columns as mutual heat sources, reboiler liquid waste heat for feed preheating), and molecular sieve adsorption conditions are optimized. The study first performs a thermodynamic consistency test on the ethanol—water system, determines optimal non-random two-liquid (NRTL) model binary interaction parameters via experimental data regression for Aspen Plus simulation. Aiming at minimum total annual cost (TAC), Aspen Plus is used to optimize process parameters (theoretical tray number, feed location, reflux ratio, side-draw position, etc.). Economic analysis shows this process reduces CO2 emission costs by 27.56%, TAC by 15.58% (to 5.123 × 106 USD·a-1), and increases ethanol purity to ＞99.6%, providing an effective solution for green, efficient separation.
A cohesion loss model for determining residual strength of deep bedded sandstone
Rock residual strength, as an important input parameter, plays an indispensable role in proposing the reasonable and scientific scheme about stope design, underground tunnel excavation and stability evaluation of deep chambers. Therefore, previous residual strength models of rocks established were reviewed. And corresponding related problems were stated. Subsequently, starting from the effects of bedding and whole life-cycle evolution process, series of triaxial mechanical tests of deep bedded s
Federated model with contrastive learning and adaptive control variates for human activity recognition
Recent attention to privacy issues demands a communication-safe method for training human activity recognition (HAR) models on client activity data. Federated learning (FL) has become a compelling technique to facilitate model training between the server and clients while preserving data privacy. However, classical FL methods often assume independent and identically distributed (IID) data among clients. This assumption does not hold true in practical scenarios. Human activity in real-world scena