Throughout human industrial development, metallic materials have played a crucial role. They form the backbone of infrastructure and are core elements in machinery and electronic devices. Due to their unique density, melting point, electrical conductivity, strength, and chemical stability, different metals exhibit irreplaceable advantages in specific fields.
Below, we provide an in-depth introduction to 25 common metals, analyzing their properties, uses, common grades, and pros and cons, while offering comparisons that highlight each metal’s characteristics to help you better understand the diversity of these fundamental materials.
Common Types of Metals
1. Iron (Fe）
Iron is one of the oldest and most important metals used in industrial applications. Although it does not possess high performance on its own, its abundance and relative ease of extraction have made it the foundation of modern metallurgy. Pure iron offers good ductility and magnetic permeability, making it particularly valuable in manufacturing electromagnetic devices.
However, pure iron is relatively soft, lacks structural strength, and readily reacts with oxygen to form iron oxide, resulting in poor corrosion resistance. These shortcomings have driven the alloying of iron to create more practical metals—namely, steel. A representative grade is Armco Pure Iron, with purity levels exceeding 99.8%.
In the construction and machinery industries, iron is typically used as a primary material, first smelted in blast furnaces into pig iron, then further processed. Although iron alone is now rarely used, its place in metallurgical history is unmatched.
2. Steel
In improving iron, one of the most significant discoveries was that adding a small amount of carbon dramatically enhances its strength and hardness. This is the basic principle of steel. Compared to pure iron, steel has higher strength and better structural stability, making it suitable for a broader range of engineering applications.
Steel can be further categorized based on its alloying elements: carbon steel, alloy steel, and stainless steel. Carbon steel, such as AISI 1018, is used for basic structural components. Alloy steel, like AISI 4140, incorporates chromium and molybdenum to improve impact resistance. Stainless steels, like 304 and 316, contain chromium and nickel for excellent corrosion resistance.
Although steel is slightly more expensive than iron, its mechanical performance is significantly better. It can be further tuned through heat treatment, making it the most widely used structural metal today. Steel also accounts for the majority of global metal production.
3. Aluminum (Al)
When it comes to lightweight structures, aluminum is undoubtedly one of the most mentioned metals. Compared to steel, aluminum has only about one-third of the density (2.70 g/cm³), making it ideal for aerospace, automotive lightweighting, and portable devices.
Another significant advantage of aluminum is its excellent corrosion resistance and electrical conductivity, especially useful in cable conductors and heat sinks. Standard aluminum alloys include 6061 (for general structural use) and 2024 (used in aerospace applications), which offer a range of strength and workability options.
Although aluminum has lower strength than steel, it can achieve higher strength through alloying and heat treatment (e.g., the T6 condition), while retaining its lightweight properties and good machinability. Aluminum is also one of the most recyclable materials with high reuse value.
4. Magnesium (Mg)
If aluminum is synonymous with “light and strong,” then magnesium represents “extreme lightness.” It is the lightest structural metal, with a density of only 1.74 g/cm³—lighter than aluminum—and is widely used in aerospace, electronic housings, and high-performance racing cars.
Magnesium alloys, such as AZ31 and ZK60, exhibit good specific strength and casting performance, making them suitable for producing complex-shaped parts. However, magnesium has relatively poor corrosion resistance and can react with water, so special surface treatments are required during use.
Another challenge with magnesium is its flammability—its powder or chips are highly flammable at high temperatures. As a result, strict controls are needed during machining and recycling. Despite this, magnesium has tremendous potential in lightweight applications, particularly in the context of automotive energy conservation and emission reduction.
5. Copper (Cu)
Compared with the structural metals mentioned earlier, copper’s value lies more in its excellent electrical and thermal conductivity. As one of the earliest metals discovered by humans, copper has long been the preferred material in electrical engineering.
Pure copper, such as C11000, is commonly used in cables, motor windings, and brushes, due to its high electrical conductivity, which is second only to silver. Additionally, copper possesses good antibacterial properties, making it widely used in medical devices and water supply systems.
The main disadvantages of copper are its relatively high cost, heavy weight, and its tendency to oxidize in air, forming a green patina. To address these issues, various copper alloys, such as brass and bronze, have been developed to expand their range of applications.
6. Brass
Brass is an alloy of copper and zinc, widely used in musical instruments, decorative items, and plumbing fixtures due to its excellent machinability, good strength, and attractive golden appearance.
Typical brass grades include C26000 and C27000, which offer good strength and corrosion resistance. Brass also has good electrical conductivity and wear resistance, making it suitable for manufacturing mechanical components and connectors.
The drawbacks of brass include susceptibility to stress corrosion cracking in ammonia environments, and although it is harder than pure copper, it is also more expensive.
7. Bronze
Bronze is a class of alloys primarily composed of copper and tin, with a long historical significance. It offers excellent wear and corrosion resistance, making it suitable for manufacturing bearings, marine components, and sculptures.
Common bronze grades include C93200 (aluminum bronze) and C95400 (tin bronze), both of which exhibit high strength and superior corrosion resistance compared to pure copper and brass.
However, bronze is relatively costly and more difficult to process, especially during casting, where strict control over composition and process is required.
8. Lead (Pb)
Among various metals, lead is known for its high density, low melting point, corrosion resistance, and ability to absorb radiation. It is commonly used in the production of batteries, radiation shielding equipment, and certain waterproofing construction materials.
Common lead grades include Pb99.9 and PbSb alloys (lead-antimony alloys), which are especially widely used in the lead-acid battery industry. Lead has good ductility and can be rolled into sheets for use in protective layers in construction or nuclear facilities.
However, lead is highly toxic, especially in compound forms (such as lead dust and vapor), which pose serious health risks. As a result, the use of lead products is strictly regulated by environmental laws, and it has been gradually phased out in drinking water systems.
10. Tin (Sn)
Similar to zinc, tin is a soft, ductile, and non-toxic metal widely used in food packaging, electrical soldering, and anti-corrosion coatings. Tin has excellent corrosion resistance and is commonly used for protective plating.
Representative applications include tinplate (tin-coated thin steel sheet) and tin-lead solder (e.g., Sn63Pb37), the latter of which is widely used in electronic component assembly. In response to increasing environmental regulations, lead-free solders such as SnAgCu alloys have also been developed.
The drawbacks of tin include low strength and relatively high cost. Pure tin can suffer from “tin pest” at low temperatures (the transformation of β-tin to α-tin), which can lead to structural damage, but it is still widely used at ambient temperatures.
14. Tungsten (W)
Tungsten is renowned for its exceptionally high melting point (3422°C) and density, making it a vital metal for manufacturing high-temperature components and high-strength materials. Tungsten steel and hard alloys (such as WC-Co) are widely used in cutting tools, molds, and armor-piercing cores.
Representative grades include W1 and WRe alloys, which are used in vacuum environments for heating elements or thermocouple wires. Tungsten is also commonly used in lighting as filament material.
Tungsten’s main advantages are its high strength, high melting point, and excellent wear resistance; however, it is difficult to process and relatively brittle. Its high density (19.3 g/cm³) also makes it suitable for radiation shielding and as a counterweight.
21. Silver (Ag)
Silver is the best-known conductor of electricity and heat, with a density of 10.49 g/cm³ and a melting point of 961.8°C. It is widely used in electronics, optics, jewelry, and photography. Its high reflectivity makes it ideal for mirror coatings and solar cells.
The downsides of silver include its relatively high cost and tendency to tarnish. Common silver alloys include sterling silver (92.5% silver), used for jewelry and cutlery.
22. Gold (Au)
Gold is favored in electronic connectors, jewelry, and currency due to its chemical inertness, electrical conductivity, and optical properties. With a high density of 19.3 g/cm³ and a melting point of 1064°C, gold offers excellent corrosion resistance and does not readily oxidize.
Its drawbacks are an extremely high cost and relatively low mechanical strength; therefore, it is usually used in alloy form to enhance durability. Gold alloys are widely used in high-end electronics and medical devices.
Types of Metal Based on the Periodic Table
1. Alkali Metals
Alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). These elements are located in Group 1 of the periodic table and share similar chemical properties.
- Characteristics: Alkali metals are highly reactive, have low densities, are soft, and have low melting points—among the smoothest of all metals. They react violently with air and water and must be stored under special conditions.
- Applications: Lithium is widely used in battery production; sodium and potassium are used in the chemical industry, pharmaceuticals, and agriculture. Potassium fertilizers are essential nutrients in modern agriculture. Due to their high reactivity, these metals are typically stored in oil or under inert gas.
2. Alkaline Earth Metals
Alkaline earth metals include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), located in Group 2 of the periodic table.
- Characteristics: These metals are moderately reactive, denser, and more complex than alkali metals and have higher melting points. They react with oxygen and water to form oxides and hydroxides and are chemically more stable.
- Applications: Magnesium is widely used in aerospace and automotive manufacturing due to its lightweight and strength. Calcium is a major component of bones and is also used as a deoxidizer in steelmaking. Strontium and barium are commonly used in fireworks and electronics.
3. Transition Metals
Transition metals include scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), etc., spanning Groups 3 to 12 of the periodic table.
- Characteristics: These metals exhibit multiple oxidation states, possess excellent mechanical properties, demonstrate high electrical conductivity, and exhibit good corrosion resistance. Many are magnetic or catalytically active, with generally high melting points and hardness.
- Applications: Iron is fundamental to the steel industry, copper is used for electrical conductors and heat exchangers, and titanium is widely applied in aerospace and medical devices. Transition metals are indispensable in manufacturing, construction, and electronics.
4. Lanthanides
Lanthanides include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).
- Characteristics: These elements share similar chemical properties, exhibit strong magnetism and exceptional optical characteristics, and have relatively high densities and moderate hardness. They are critical components of the rare earth group.
- Applications: Neodymium magnets are used in motors and wind turbines; cerium is essential in catalytic converters and glass polishing. Lanthanides are widely used in high-tech industries and considered strategic resources.
5. Actinides
Actinides include actinium (Ac), thorium (Th), protactinium (Pa), uranium (U), neptunium (Np), plutonium (Pu), and other radioactive elements.
- Characteristics: These metals are typically radioactive, have high densities, and exhibit complex chemistry. They are highly active in nuclear reactions and require strict safety protocols.
- Applications: Uranium and plutonium are the primary materials in nuclear fuel and weapons. Thorium is gaining attention as a potential future fuel. Actinides are also used in the production of radioactive isotopes and for scientific research.
6. Post-Transition Metals
Post-transition metals include aluminum (Al), tin (Sn), lead (Pb), indium (In), gallium (Ga), bismuth (Bi), and thallium (Tl).
- Characteristics: These metals are soft and ductile, have medium to high densities, and possess electrical conductivity and melting points between those of typical metals and nonmetals. Their chemical reactivity is moderate.
- Applications: Aluminum is widely used in transportation and construction; tin is used in solder and protective coatings; lead is used in batteries and radiation shielding. Gallium and indium are essential materials in semiconductor and optoelectronic devices.
7. Noble Metals
Noble metals include gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), and osmium (Os).
- Characteristics: Noble metals are chemically stable, highly resistant to corrosion, excellent electrical conductors, and highly ductile with a shiny luster.
- Applications: Extensively used in jewelry, currency reserves, and high-end electronic products. Platinum-group metals play a crucial role as catalysts in automotive exhaust treatment and various chemical processes. Gold and silver are highly valuable due to their rarity.
8. Rare Earth Metals
Strictly speaking, rare earth metals refer mainly to the lanthanides and partially to the actinides. They belong to Categories 4 and 5 above but are often studied and applied as a distinct group due to their unique properties and strategic importance.
9. Base Metals
Base metals are not a formal category in the periodic table but a commercial and industrial term. They typically refer to common, inexpensive, and widely used metals such as iron, copper, aluminum, nickel, zinc, lead, and tin. These usually fall under the categories of transition metals, post-transition metals, and alkaline earth metals.
Physical Properties of Metals
Density
Metals generally have high density, meaning a high mass-to-volume ratio. Density affects the weight and application of metals — for example, aluminum’s low density makes it suitable for lightweight designs, while tungsten’s high density is ideal for protective materials.
Melting and Boiling Points
Most metals have high melting and boiling points, allowing them to remain stable in high-temperature environments. The range varies greatly among metals; for instance, tungsten has an extremely high melting point (3422°C), while mercury is liquid at room temperature.
Electrical Conductivity
Metals contain many free electrons, enabling excellent electrical conductivity. Silver and copper are the best conductors and are widely used in wires and electronic devices.
Thermal Conductivity
Metals efficiently transfer heat, exhibiting good thermal conductivity. Copper and silver are particularly outstanding and commonly used in heat sink materials.
Ductility and Malleability
Metals can be stretched into wires (ductility) or hammered into thin sheets (malleability), thanks to the non-directional nature of metallic bonds and the ease of atomic layer slippage in their crystal structure.
Luster
Metal surfaces exhibit a distinct metallic luster due to the ability of free electrons to reflect light.
Magnetism
Some metals such as iron, cobalt, and nickel exhibit ferromagnetism — they can be attracted to magnets and retain magnetic properties.
Chemical Properties of Metals
Reactivity
Metals vary in their reactivity with the environment. Alkali metals react vigorously with water and air to form oxides or hydroxides, while noble metals like gold and platinum are highly stable and resistant to oxidation.
Oxidation and Reduction
Metals tend to lose electrons (oxidation) and form positive ions, making them good reducing agents. For example, iron oxidizes in moist environments to form rust.
Reactions with Acids and Bases
Most metals react with acids to produce salts and hydrogen gas. Some reactive metals can also react with bases to form salts and release hydrogen.
Corrosion
Metal surfaces are prone to corrosion, such as iron rusting and copper forming a green patina. Corrosion resistance varies significantly among metals; stainless steel, for instance, resists corrosion due to added chromium.
Alloy Formation
Metals can combine with other metals or non-metals to form alloys, enhancing their properties. For example, steel is an alloy of iron and carbon, offering improved strength and toughness.
FAQ About Types of Metals
Metals typically have good electrical and thermal conductivity, ductility, malleability, and metallic luster, and are mostly solid. Non-metals generally do not conduct electricity, have poor thermal conductivity, and are brittle.
An alloy is a material composed of two or more metals or a combination of metals and non-metals, designed to improve mechanical strength, corrosion resistance, or other physical and chemical properties.
Iron is a pure element, softer and more prone to rust. Steel is an alloy of iron with carbon and other elements, offering higher strength and better corrosion resistance — making it more suitable for construction.
Aluminum has low density, a high strength-to-weight ratio, and good corrosion resistance, which helps reduce weight and improve fuel efficiency and performance.
Common grades include 304, 316, and 430. 304 is widely used for general purposes, 316 offers superior corrosion resistance, and 430 is a ferritic grade with stronger magnetic properties.
Advantages include extremely low weight and relatively high strength. Disadvantages include poor corrosion resistance and flammability, requiring surface treatments and safety precautions during handling.
Electrical conductivity is essential for transmitting electricity, while thermal conductivity affects heat management — both are critical in electronics, power systems, and mechanical components.
Ductility is the ability to stretch into wires; malleability is the ability to be hammered into sheets. Good ductility and malleability enable easier forming of complex shapes.
Corrosion can be prevented using coatings, plating, corrosion-resistant alloys, and cathodic protection to extend service life.
Hardness is the ability of a material to resist deformation or scratching. Common testing methods include Brinell, Rockwell, and Vickers hardness tests.
Magnetism arises from the alignment of electron spins. Iron, cobalt, and nickel are typical ferromagnetic metals.
They are used in high-performance magnets, catalysts, electronic displays, and new energy technologies.
Precious metals like gold, silver, and platinum are rare and corrosion-resistant, while base metals like iron and copper are common and widely used.
It is the maximum stress a metal can endure under repeated loading. It determines the durability and safety of structural components.
High temperatures can reduce strength and hardness, increase creep and oxidation rates, and shorten service life.
Consider mechanical properties, corrosion resistance, workability, cost, and environmental factors.
Welding creates a permanent joint suitable for complex structures, while mechanical fastening allows disassembly and easier maintenance.
Recycling conserves resources and reduces pollution. Commonly recycled metals include aluminum, copper, steel, and nickel.
Crystal structure refers to how atoms are arranged. It influences strength, ductility, and hardness — for example, face-centered cubic structures generally offer better ductility.
