A Deep Dive into Zinc Alloy Composites: A Review of Microstructures and Properties of Felled Metal Alloy Composites (Al-17Si-Gr-Cf)

This technical summary is based on the academic paper "Review of Microstructures and Properties of Felled Metal Alloy Composites (Al-17Si-Gr-Cf)" by Manas Mayank and Dr. Manish Gangil, published in Research Journal of Engineering Technology and Medical Sciences (2020).

Keywords

Primary Keyword: Zinc Alloy Composite Properties
Secondary Keywords: High Pressure Die Casting, Zamak, ZA Alloys, Microstructure, Mechanical Properties, Wear Resistance

Executive Summary

The Challenge: Selecting the right zinc-based alloy and manufacturing process requires a deep understanding of how composition and processing parameters impact final microstructure and mechanical performance.
The Method: This paper provides a comprehensive review of the relationships between processing methods (like die-casting), microstructure, and key mechanical properties (hardness, wear, creep) for common zinc-based alloys.
The Key Breakthrough: The review clearly links specific alloying elements like aluminum and copper to distinct microstructural features and wear resistance characteristics, providing a guide for material selection.
The Bottom Line: The performance of zinc alloy components is fundamentally determined in the as-cast condition, making the choice of alloy and foundry process—particularly hot-chamber vs. cold-chamber die-casting—the most critical decision for engineers.

The Challenge: Why This Research Matters for HPDC Professionals

Zinc-based alloys (referred to as "metal alloys composite" in the paper) are workhorses in the manufacturing industry, accounting for about 15% of global consumption for parts in automotive, electronics, and consumer goods. Their low melting temperature, high fluidity, and excellent finishing characteristics make them ideal for high-pressure die-casting of complex, thin-walled components.

However, the performance of these parts is not guaranteed. Engineers face the challenge of navigating a wide variety of alloys (like the Zamak and ZA series) and processing methods. Without a clear understanding of the underlying material science, it's difficult to predict how a component will behave under mechanical stress, at elevated temperatures, or over long periods (aging). This paper addresses this critical knowledge gap by reviewing the direct links between an alloy's composition, its processing, the resulting microstructure, and its final in-service performance.

The Approach: Unpacking the Methodology

As a comprehensive review, this paper synthesizes knowledge on the primary manufacturing and analysis methods for zinc-based alloys. The key processes discussed are critical for any HPDC professional to understand:

Method 1: High-Pressure Die-Casting (Hot & Cold Chamber)
The paper highlights that 90-95% of zinc alloy components are produced via the hot-chamber die-casting process. In this method, the injection system's "gooseneck" is submerged in the molten metal, allowing for fast cycle times and efficient production. However, for alloys with higher aluminum content and melting temperatures, such as ZA27, cold-chamber die-casting is required. In this process, molten metal is ladled into a "shot sleeve" separate from the furnace, preventing corrosive attack on the injection system components.

Method 2: Other Casting Processes
For applications requiring different properties or production volumes, other methods are used. Gravity and sand casting are employed for components like press dies (using Kirksite, or Zamak 2). Spin casting is used for producing small, detailed parts for the fashion industry, while slush casting is used to create hollow items like lamp bases.

Method 3: Microstructural Analysis
The review emphasizes the importance of analyzing the alloy's microstructure to understand its properties. The paper describes the use of metallographic analysis, where samples are etched to reveal features like the primary Zn-rich dendrites and the surrounding eutectic or eutectoid structures. Techniques like scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) are used to identify the distribution of different phases, such as the Al-rich and Cu-rich phases within the zinc matrix.

The Breakthrough: Key Findings & Data

This review consolidates several critical findings that directly impact material selection and process design in HPDC.

Finding 1: Alloying Elements Dictate Performance

The properties of zinc alloys are finely tuned by small additions of other elements. The paper notes that Copper (Cu) is added to increase tensile strength, hardness, and wear resistance, as well as creep behavior. For instance, in Zamak 2, a Cu-rich ε-phase (CuZn) can be found, contributing to its hardness. In contrast, a small amount of Magnesium (Mg) is added primarily to inhibit inter-granular corrosion, a crucial factor for long-term durability.

Finding 2: Microstructure is the Key to Wear Resistance

The paper establishes a direct link between an alloy's microstructure and its wear performance. For hypo-eutectic alloys like Zamak 3, the low hardness (due to the primary Zn-rich phase) results in a higher friction coefficient and wear rate in dry conditions against steel. Conversely, the harder Zamak 2 alloy, with its higher copper content, shows different wear behavior. The paper reports that alloys with higher aluminum content (e.g., ZA27) can form a protective oxide layer on the wear track, improving their resistance compared to alloys that form a more limited oxide layer.

Practical Implications for R&D and Operations

For Process Engineers: This study reinforces that the choice between hot-chamber and cold-chamber die-casting is not arbitrary. It is dictated by the alloy's composition, specifically its aluminum content. Using a high-Al alloy like ZA27 in a hot-chamber machine can lead to premature failure of the injection system.
For Quality Control Teams: The microstructural analysis described in the paper provides a powerful tool for quality assurance. The presence and morphology of primary Zn-rich dendrites versus the eutectic structure directly correlate to the final mechanical properties. This can be used as a criterion for process validation and root cause analysis of part failures.
For Design Engineers: The findings highlight both the advantages and limitations of zinc alloys. Their high fluidity allows for casting extremely thin sections (down to 0.13 mm), enabling complex designs. However, the paper explicitly notes a reduction in performance above 80-90°C and after long-term exposure at room temperature (aging), which must be factored into the design for any load-bearing or dimensionally critical application.

Paper Details

Review of Microstructures and Properties of Felled Metal Alloy Composites (Al-17Si-Gr-Cf)

1. Overview:

Title: Review of Microstructures and Properties of Felled Metal Alloy Composites (Al-17Si-Gr-Cf)
Author: MANAS MAYANK, DR. MANISH GANGIL
Year of publication: 2020
Journal/academic society of publication: Research Journal of Engineering Technology and Medical Sciences (ISSN: 2582-6212), Special Issue 2
Keywords: Metal alloys, zamak alloy, ZA, aging

2. Abstract:

According to market data, about 15% of world metal alloys composite consumption is devoted to the production of metal alloys composite that are used for manufacturing automotive parts, electronic/electrical systems and also, water taps and sanitary fittings, household articles, fashion goods, etc. These alloys are characterized by low melting points and high fluidity that make them suitable for foundry applications. Typically, they are processed by hot chamber high-pressure die-casting where can be cast to thicknesses as low as 0.13 mm. The die-cast metal alloys composite alloys possess an attractive combination of mechanical properties, permitting them to be applied in a wide variety of functional applications. However, depending on the alloying elements and purposes, some metal alloys composite can be processed also by cold chamber die-casting, gravity, or sand casting as well as spin casting and slush casting. In this paper, a detailed overview of the current knowledge in the relationships between processing, microstructure and mechanical properties of metal alloys composite will be described. In detail, the evolution of the microstructure, the dimensional stability and aging phenomena are described. Furthermore, a thorough discussion on mechanical properties, as such as hardness, tensile, creep, and wear properties of metal alloys composite is presented.

3. Introduction:

A metal alloy composite is the fourth metal in the world, after iron, aluminum and copper. About 15% of world metal alloys composite is used as base metal for the production of metal alloys composite-base alloys. Some are available as wrought alloys, but metal alloys composite-base alloys possess a series of properties that makes them particularly attractive for die-casting manufacturing and foundry technologies. They are characterized by a low melting temperature, low energy consumption, long die life, and high fluidity, which helps in filling complex molds and very thin sections (down to 0.13 mm). They show good mechanical properties, including bearing and wear properties, and are easily finished and plated.

4. Summary of the study:

Background of the research topic:

The study is situated in the context of zinc-based die-casting alloys, which the paper refers to as "metal alloys composite." These materials are widely used for functional and decorative components due to their advantageous casting properties. The paper addresses the need for a consolidated understanding of the factors governing their performance.

Status of previous research:

The paper reviews existing literature on zinc alloys, citing numerous studies that have investigated the effects of alloying elements (Al, Cu, Mg), processing methods (die-casting, gravity casting), and service conditions on the microstructure and mechanical properties, including wear, creep, and aging.

Purpose of the study:

The purpose is to provide a detailed overview of the current knowledge regarding the relationships between processing, microstructure, and mechanical properties of zinc-based alloys. It aims to describe the evolution of microstructure, dimensional stability, aging phenomena, and key mechanical properties to guide their application.

Core study:

The core of the study is a review that connects the manufacturing processes of zinc alloys to their resulting microstructures and performance characteristics. It categorizes alloys based on their position in the Zn-Al phase diagram (hypoeutectic, hypereutectic, hypereutectoid) and discusses how this influences their microstructure (e.g., primary Zn-rich dendrites in Zamak alloys). It then delves into performance aspects like wear and cavitation resistance, explaining how factors like hardness and oxide formation on the wear track, which are tied to composition and microstructure, determine the material's durability.

5. Research Methodology

Research Design:

The paper is a literature review. It synthesizes and discusses findings from a range of previously published academic papers and technical sources on the topic of zinc-based alloys.

Data Collection and Analysis Methods:

The study collects information from existing scientific literature. The analysis is qualitative, summarizing and correlating findings related to processing techniques (die-casting, sand casting, etc.), microstructural characterization (e.g., SEM-EDS), and mechanical property testing (e.g., wear tests).

Research Topics and Scope:

The scope covers zinc-based casting alloys, primarily the Zamak and ZA series. The topics include:
- An overview of global consumption and applications.
- A description of various manufacturing processes, with a focus on die-casting.
- A detailed discussion of the microstructures of different alloy types.
- An analysis of mechanical performance, with a specific focus on wear and cavitation resistance.
- A discussion on the role of alloying elements like Al, Cu, and Mg.

6. Key Results:

Key Results:

Zinc-based alloys are primarily processed by hot-chamber die-casting (90-95% of alloys) due to their low melting point, but high-Al alloys like ZA27 require cold-chamber die-casting.
The microstructure of these alloys, which dictates their properties, is dependent on the aluminum content and cooling rate. Hypoeutectic alloys like Zamak consist of primary Zn-rich dendrites surrounded by a eutectic structure.
Alloying elements have specific functions: Copper increases hardness and wear resistance, while Magnesium inhibits inter-granular corrosion.
Wear resistance is strongly linked to microstructure and hardness. For example, the lower hardness of Zamak 3 results in higher friction and wear rates compared to other alloys in dry conditions.
These alloys are typically used in the as-cast condition, as cold working carries a risk of cracking and age hardening has limited effectiveness.

Figure Name List:

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7. Conclusion:

The paper provides an overview of the properties of Zn alloys, with particular attention to the correlation between microstructure and performance. After summarizing commercial alloys and manufacturing processes, microstructural properties are described with a focus on Zn-Al and Zn-Cu systems. Various aspects such as tensile properties, wear resistance, creep behavior, and corrosion resistance are discussed, along with the effect of natural aging. The general aim is to allow the reader to better understand the specific applications suitable for this family of alloys.

8. References:

[1]. Liu, Z.; Li, R.; Jiang, R.; Li, X.; Zhang, M. E_ects of Al addition on the structure and mechanical properties of Zn alloys. J. Alloys Compd. 2016, 687, 885–892.
[2]. Hekimoglu, A.P.; Sava skan, T. Structure and mechanical properties of Zn-(5–25) Al alloys. Int. J. Mater. Res. 2014, 105, 1084–1089.
[3]. Pola, A.; Montesano, L.; Roberti, R. Nuove Leghe di Metal alloys compositeo per L'industria del Design. In Proceedings of the 30th Convegno Nazionale AIM, Brescia, Italy, 10–12 November 2010.
[4]. Sava skan, T.; Hekimoglu, A.P.; Pürçek, G. E_ect of copper content on the mechanical and sliding wear properties of monotectoid-based metal alloys composite-aluminium-copper alloys. Tribol. Int. 2004, 37, 45–50.
[5]. Luo, X.-P.; Xia, L.-T.; Zhang, M.-G. E_ect of di_erent_Al content on the microstructure, mechanical and friction properties of high aluminum metal alloys composite-based alloys. J. Adv. Microsc. Res. 2011, 6, 301–305.
[6]. Türk, A.; Durman, M.; Kayali, E.S. The e_ect of manganese on the microstructure and mechanical properties of metal alloys composite-aluminium based ZA-8 alloy. J. Mater. Sci. 2007, 42, 8298-8305.
[7]. Li, M.; Lu, S.; Long, F.; Sheng, M.; Geng, H.; Liu, W. E_ect of Y Addition on the Mechanical Properties and Microstructure of Zn-Al Alloys. JOM 2015, 67, 922–928.
[8]. Gancarz, T.; Cempura, G. Characterization of ZnAl cast alloys with Li addition. Mater. Des. 2016, 104, 51–59.
[9]. Krupi'nska, B. Structure and Properties of Zn-Al–Cu Alloys with Alloying Additives. Adv. Struct. Mater. 2015, 70, 341-349.
[10]. Choudhury, P.; Das, K.; Das, S. Evolution of as-cast and heat-treated microstructure of a commercial bearing alloy. Mater. Sci. Eng. A 2005, 398, 332-343.
[11] Sava skan, T.; Bican, O. E_ects of silicon content on the microstructural features and mechanical and sliding wear properties of Zn–40Al–2Cu–(0–5)Si alloys. Mater. Sci. Eng. A 2005, 404, 259–269.
[12]. Goodwin, F.E.; Kallien, L. Improving the Relationship between Processing and Properties of Metal alloys composite Die Casting: Developments in Creep and Ageing Correlations. SAE Int. J. Mater. Manuf. 2011, 4, 1188–1197.
[13]. Dorantes-Rosales, H.J.; López-Hirata, V.M.; Hernández-Santiago, F.; Saucedo-Muñoz, M.L.; Paniagua-Mercado, A.M. E_ect of Ag addition to Zn22 mass%Al2 mass%Cu alloy on the four-phase reaction. Mater. Trans. 2018, 59, 717–723.
[14]. Chen, Y.; Tu, M. Dimensional shrinkage of supersaturated ZA27Cul and ZA27Cu2 alloys. Mater. Sci. Techol. 1998, 14,473–475.
[15]. Chen, H.; Xin, X.; Dong, D.Y.; Ren, Y.P.; Hao, S.M. Study on the stability of T0 phase in the Al-Zn-Cu ternary system. Acta Metall. Sinca 2004, 17, 269–273.
[16]. Lee, P.P.; Savaskan, T.; Laufer, E. Wear resistance and microstructure of Zn-Al-Si ans Zn-Al-Cu alloys. Wear 1987, 117, 79–89.
[17]. Türk, A.; Kurnaz, C.; Sevik, H. Comparison of the wear properties of modified ZA-8 alloys and conventional bearing bronze. Mater. Des. 2007, 28, 1889–1897.
1. Sava skan, T.; Maleki, R.A. Friction and wear properties of Zn-25Al-based bearing alloys. Tribol. Trans. 2014,57, 435–444.
[19]. Babic, M.; Mitrovic, S.; Jeremic, B. The influence of heat treatment on the sliding wear behavior of a ZA-27 alloy. Tribol. Int. 2010, 43, 16–21.
[20[. Pürçek, G.; Savaskan, T.; Küçükömeroglu, T.; Murphy, S. Dry sliding friction and wear properties of metal alloys composite-based alloys. Wear 2002, 252, 894–901.

Expert Q&A: Your Top Questions Answered

Q1: What are the primary roles of copper and magnesium as alloying elements in these zinc-based alloys?

A1: According to the paper, copper is added to increase the alloy's performance in terms of tensile strength, hardness, and wear resistance, as well as its creep behavior [16]. Magnesium is added in small amounts primarily to inhibit inter-granular corrosion [17], which is crucial for the long-term integrity of the component, although the paper notes its need is less critical in modern high-purity zinc.

Q2: The paper mentions both hot-chamber and cold-chamber die-casting. When is one required over the other?

A2: The choice depends on the alloy's composition, specifically its aluminum content and melting temperature. The paper states that about 90-95% of these alloys are processed via hot-chamber die-casting due to their low melting temperatures [5]. However, when the amount of alloying elements increases, as in the case of ZA27, the melting temperature rises and the alloy becomes more aggressive. This requires the use of cold-chamber die-casting to avoid having the injection system constantly submerged in the corrosive molten metal.

Q3: Why are these zinc alloys typically used in the "as-cast" condition without further heat treatment or cold working?

A3: The paper explains that these alloys do not usually undergo cold working or heat treatment for two main reasons. First, there is a significant risk of crack formation during cold working due to their low plasticity. Second, the effectiveness of age hardening treatments is limited [11]. Therefore, the final properties are almost entirely determined by the casting process itself, making the initial process control paramount.

Q4: The review mentions that Zamak 3 has a higher wear rate than other alloys. What is the microstructural reason for this?

A4: The paper attributes the higher friction coefficient and wear rate of Zamak 3 to its low hardness. This low hardness is a direct result of its microstructure, which is characterized by a primary Zn-rich phase [10, 11]. In contrast, alloys with higher copper content (like Zamak 2) or higher aluminum content are harder and can exhibit different, often better, wear resistance.

Q5: How does the high fluidity of these alloys benefit component design?

A5: The paper highlights that the high fluidity of these alloys is a key advantage for foundry applications. This property helps in filling complex mold cavities and allows for the casting of very thin sections. The text specifies that thicknesses can be "typically as low as 0.75 mm or even down to 0.13 mm" [7], enabling the production of intricate, lightweight, and near-net-shape parts that would be difficult to achieve with other materials.

Conclusion: Paving the Way for Higher Quality and Productivity

This comprehensive review underscores a fundamental principle for anyone working with zinc die-casting: control the process, and you control the part. The research clearly demonstrates how Zinc Alloy Composite Properties are a direct function of the initial alloy selection and the chosen manufacturing method. By understanding the links between composition, microstructure, and performance—particularly wear resistance—engineering and production teams can make more informed decisions, reduce failures, and optimize component design.

At CASTMAN, we are committed to applying the latest industry research to help our customers achieve higher productivity and quality. If the challenges discussed in this paper align with your operational goals, contact our engineering team to explore how these principles can be implemented in your components.

Copyright Information

This content is a summary and analysis based on the paper "Review of Microstructures and Properties of Felled Metal Alloy Composites (Al-17Si-Gr-Cf)" by "Manas Mayank and Dr. Manish Gangil".

Source: Research Journal of Engineering Technology and Medical Sciences (ISSN: 2582-6212), Special Issue 2 (2020), Available at www.rjetm.in/

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Tags: AUTOMOTIVE Parts; , Alloying elements; , CAD; , Die casting; , High pressure die casting; , Mechanical Property; , Microstructure; , Quality Control; , Sand casting