Is Magnesium Stronger Than Zinc? Comparing Material Strength and Properties

December 28, 2025 •

4 min read

According to materials science data, common zinc alloys like Zamak 5 can achieve a tensile strength of around 328 MPa, which is a higher raw figure than the roughly 230 MPa found in standard magnesium alloys like AZ91D. However, a direct comparison depends entirely on the specific application and the definition of "strength" being used.

Quick Summary

Zinc alloys often possess higher raw tensile strength and superior corrosion resistance in many environments, making them ideal for durability. In contrast, magnesium offers a much higher strength-to-weight ratio due to its significantly lower density, favoring lightweight construction.

Key Points

Specific Strength: Due to its lower density, magnesium has a higher strength-to-weight ratio, making it superior for lightweight applications.
Tensile Strength: Zinc alloys generally exhibit higher raw tensile strength, meaning they can withstand more pulling force before breaking.
Corrosion Resistance: Zinc offers better inherent corrosion resistance in many environments compared to highly reactive magnesium, which requires protective coatings.
Manufacturing Ease: Zinc is easier and cheaper to die-cast, with a lower melting point and better fluidity for complex, high-volume parts.
Application-Dependent: The better metal depends on the project; magnesium is for weight-sensitive applications (aerospace), while zinc is for durability and cost-effectiveness (general hardware).

Defining Material Strength

Before addressing whether magnesium is stronger than zinc, it is crucial to clarify what "strength" means in a materials science context. Strength is not a single value but a collection of mechanical properties. These include tensile strength (resistance to being pulled apart), yield strength (resistance to permanent deformation), fatigue resistance (resistance to failure under repeated stress), and specific strength (the ratio of strength to density). Pure elemental metals are rarely used for structural applications, with engineers almost always relying on alloys to enhance desired properties. Therefore, the comparison relies heavily on the alloyed forms of both metals.

Magnesium: The Lightweight Champion

Magnesium is known as the lightest structural metal available, boasting an exceptionally high strength-to-weight ratio. Its density is roughly 1.8 g/cm³, about 73% lower than that of zinc alloys, making it ideal for applications where weight reduction is paramount. This property makes magnesium a star performer in the aerospace, automotive, and high-end electronics industries, where every gram saved contributes to better fuel efficiency or portability. Magnesium alloys, such as AZ91D, are engineered to balance strength and weight for demanding uses.

Key Characteristics of Magnesium Alloys:

Low Density: Drastically reduces the weight of components.
High Specific Strength: Offers excellent performance for its mass, a critical factor in aviation.
Good Damping: Absorbs vibrations effectively, which is beneficial for reducing noise and wear in machinery.
Reactive Nature: Magnesium is highly reactive and susceptible to corrosion, requiring protective coatings or careful alloying to be used in most environments.

Zinc: The Durable Workhorse

Zinc alloys, particularly the Zamak family (which contain aluminum, magnesium, and copper), are revered for their strength and durability. With a density of approximately 6.6 g/cm³, they are much heavier than magnesium but offer excellent raw tensile and yield strength. Zinc's superior castability is another significant advantage. Its low melting point and high fluidity make it easier and more energy-efficient to cast into complex, intricate shapes in high-volume production runs. Zinc is also widely known for its role in galvanization, where it provides exceptional corrosion protection for steel.

Key Characteristics of Zinc Alloys:

High Raw Strength: Alloys like Zamak 5 and ZA-8 boast high tensile and yield strengths, suitable for robust components.
Excellent Castability: The low melting point allows for fast, precise, and energy-efficient die casting.
Good Corrosion Resistance: Provides durable protection, especially in mild to standard atmospheric conditions.
Cost-Effective: Often more affordable in both raw material cost and processing, making it a budget-friendly option for many applications.

Magnesium vs. Zinc: A Head-to-Head Comparison Table


Property	Magnesium Alloys (e.g., AZ91D)	Zinc Alloys (e.g., Zamak 5)	Winner based on Property
Density	Very low (approx. 1.8 g/cm³)	High (approx. 6.6 g/cm³)	Magnesium
Tensile Strength	Lower raw strength (~230 MPa)	Higher raw strength (~328 MPa)	Zinc
Specific Strength	Very high	Low	Magnesium
Corrosion Resistance	Poor (requires protective coatings)	Good (inherently better in mild settings)	Zinc
Castability	Higher melting point; requires cold chamber casting	Lower melting point; allows efficient hot chamber casting	Zinc
Cost	Higher material and processing costs	Lower cost, especially in high volume	Zinc
Best Use Case	Lightweighting (aerospace, electronics)	High-volume durable parts (automotive, hardware)	Depends on application

Alloying Effects and Synergies

The comparison of pure metals is academic, as real-world applications use alloys designed for specific performance traits. For example, zinc itself is often added to magnesium alloys like AZ91D to enhance their properties. Conversely, zinc alloys like Zamak contain small amounts of magnesium to refine the grain structure, improving hardness and strength. The development of new alloys with rare earth elements continues to improve the corrosion resistance of magnesium, though it still requires more protection than zinc in harsh conditions.

Practical Applications Showcase

Magnesium's role:
1. Aerospace Components: For things like seat frames, where weight savings directly impact fuel efficiency.
2. High-Performance Automotive: Used for parts like transmission cases or steering wheel cores in premium cars to reduce overall weight.
3. Consumer Electronics: Laptop and smartphone chassis often utilize magnesium alloys for a lightweight yet rigid structure.
Zinc's role:
1. Automotive Interior Parts: Items like door handles and brackets benefit from zinc's precision castability and durability.
2. Hardware and Fasteners: Construction and hardware industries rely on zinc's corrosion resistance for items like bolts and hinges.
3. Electronics Casings: Zinc is frequently used for dense, durable casings that require tight tolerances and structural integrity.

Conclusion: Which is Truly Stronger?

There is no single answer to whether magnesium is stronger than zinc, as each metal excels in different areas. For sheer tensile strength, zinc alloys can surpass magnesium alloys. For applications where weight is the most critical factor, magnesium's exceptionally high strength-to-weight ratio makes it the unequivocally stronger choice. Zinc also holds a clear advantage in castability, cost, and innate corrosion resistance, making it the preferred option for many high-volume, durable parts. Ultimately, the "stronger" metal is the one whose unique properties best align with the specific demands of the intended product or engineering challenge.

For further insights into the benefits of magnesium and zinc in manufacturing, consider exploring resources like this comparison of casting alloys: Anebon Article

Frequently Asked Questions

Magnesium is significantly lighter than zinc. With a density of only about 1.8 g/cm³, magnesium is roughly 73% lighter than zinc's 6.6 g/cm³.

Yes, pure magnesium is more reactive and corrodes faster than pure zinc. However, magnesium alloys can be protected with special coatings to improve their corrosion resistance in various environments.

Zinc alloys are often preferred for high-volume manufacturing due to their lower material cost, easier and more energy-efficient die casting process, and better innate corrosion resistance, which reduces overall production costs.

Yes, zinc is often added to magnesium to create stronger alloys. For instance, AZ91D is a common magnesium alloy that contains about 9% aluminum and 1% zinc to enhance its strength.

Zinc generally has better castability for intricate shapes. Its low melting point and high fluidity allow it to fill complex molds more easily and with greater precision during die casting.

Specific strength is the ratio of a material's strength to its density. It is highly important for magnesium because its high specific strength makes it an excellent material for aerospace and automotive parts where reducing weight is critical for performance and fuel efficiency.

Yes, magnesium is generally more expensive than zinc, primarily due to its more complex extraction process and the need for additional protective coatings to prevent corrosion.