The emergence of bronze around 3300 BC to 1200 BC marked the beginning of humans using alloys. Alloys have undergone a long process of development, from ancient bronze to modern high-performance alloys.
Technological progress at each stage has continually improved the performance and application range of alloys, promoting their widespread use in various fields.
Alloy Definition
An alloy is a metallic material composed of two or more elements, at least one of which is a metal. By mixing these elements, alloys improve their properties, giving them better properties than a single metal, such as strength, hardness, corrosion resistance, wear resistance, etc.
How are Alloys Made
There are many different alloys in nature that are typically formed through natural geological and chemical processes.
One of the most well-known natural alloys is the iron-nickel alloy found in meteorites, which usually contains around 90% iron and 10% nickel. This forms various mineral phases, including “metallic nickel-iron” (kamacite) and “nickel iron-nickel” (taenite) in iron-nickel alloys.
In most cases, alloy formation can be achieved through smelting and synthesis technology :
Melting Method
Melting method: The most common method of alloy production involves melting and mixing alloying elements at high temperatures, usually in a furnace.
Mechanical alloying: Metal powders are mixed using mechanical force (such as ball milling) to undergo physical reactions and form alloys. This method can produce ultrafine-grained alloys.
Chemical synthesis: Chemical reactions synthesize alloys in the gas phase and deposit them onto substrates to form films or coatings, or alloying elements are reduced from their compounds by chemical reactions and mixed to form alloys.
This also includes powder metallurgy, magnetron sputtering, cold processing, and heat treatment.
Types of Alloys
There are many types of alloys. Common alloys can be classified according to their main components, application areas, and performance characteristics. Some common alloy types include steel alloy, aluminum alloy, copper alloy, nickel alloy, titanium alloy, and special alloys.
Steel Alloys
| Steel Alloys | Main Components | Characteristics | Applications | Common Grades (ASTM) |
| Carbon Steel | Iron + Carbon | High strength, hardness, cost-effective | Construction structures, mechanical parts, automotive manufacturing | ASTM A36, ASTM A106, ASTM A500 |
| Alloy Steel | Iron + Carbon + Alloy Elements (e.g., Chromium, Nickel) | Excellent strength, wear resistance, and corrosion resistance | Tools, mechanical components, automotive parts | ASTM A514, ASTM A572 |
| Stainless Steel | Iron + Chromium (at least 10.5%) + Nickel | Excellent corrosion resistance and high-temperature performance | Household utensils, chemical equipment, medical instruments | ASTM A240 (304, 316), ASTM A276 (410, 430) |
Aluminum Alloys
| Aluminum Alloys | Main Components | Characteristics | Applications | Common Grades (ASTM) |
| Pure Aluminum | Aluminum | Lightweight, corrosion-resistant, but lower strength | Aerospace, automotive, building materials | ASTM B209 (1100, 1050) |
| Aluminum-Copper Alloy | Aluminum + Copper | High strength, excellent mechanical properties | Aircraft, automotive parts, structural materials | ASTM B209 (2024), ASTM B211 (2011) |
| Aluminum-Zinc Alloy | Aluminum + Zinc | Excellent strength and corrosion resistance | Building materials, automotive components | ASTM B209 (7075), ASTM B211 (7050) |
Copper Alloys
| Copper Alloys | Main Components | Characteristics | Applications | Common Grades (ASTM) |
| Brass | Copper + Zinc | Good machinability and corrosion resistance | Pipe fittings, musical instruments, decorations | ASTM B36 (C26000), ASTM B124 (C36000) |
| Bronze | Copper + Tin | Good wear resistance and corrosion resistance | Artifacts, statues, mechanical components | ASTM B505 (C93200), ASTM B150 (C95400) |
| Copper-Nickel Alloy | Copper + Nickel | Excellent corrosion resistance and strength | Marine environment equipment, coins, medical instruments | ASTM B122 (CuNi 90/10, CuNi 70/30) |
Nickel Alloys
| Nickel-Based Alloy | Nickel + Alloy Elements (e.g., Chromium, Molybdenum) | Excellent high-temperature performance and corrosion resistance | Aerospace, chemical industry, power generation equipment | ASTM B443 (Inconel 625), ASTM B637 (Inconel 718) |
| Nickel-Iron Alloy | Nickel + Iron | Good magnetic properties and corrosion resistance | Magnetic materials, electrical equipment | ASTM A353 (Invar 36), ASTM A753 (Mu-metal) |
Titanium Alloys
| Titanium Alloys | Main Components | Characteristics | Applications | Common Grades (ASTM) |
| Alpha Alloy | Titanium + Aluminum + Tin | High strength, good corrosion resistance | Aerospace, medical implants | ASTM B348 (Grade 5), ASTM F136 (Ti-6Al-4V) |
| Beta Alloy | Titanium + Alloy Elements (e.g., Molybdenum, Chromium) | High strength, high elastic modulus | Aircraft, sports equipment | ASTM B348 (Grade 19), ASTM F2063 (Ti-15V-3Cr-3Sn-3Al) |
High-Temperature Alloys
| High-Temperature Alloys | Main Components | Characteristics | Applications | Common Grades (ASTM) |
| Nickel-Based High-Temperature Alloy | Nickel + Alloy Elements (e.g., Chromium, Molybdenum) | Excellent high-temperature strength and corrosion resistance | Engine components, gas turbines | ASTM B637 (Inconel 718), ASTM B408 (Hastelloy X) |
| Cobalt-Based High-Temperature Alloy | Cobalt + Alloy Elements (e.g., Chromium, Aluminum) | Excellent oxidation resistance and corrosion resistance | Aerospace engines, turbine blades | ASTM F90 (Haynes 188), ASTM B815 (L-605) |
Special Alloys
| Special Alloys | Main Components | Characteristics | Applications | Common Grades (ASTM) |
| Shape Memory Alloy | Nickel + Titanium | Can recover its original shape at specific temperatures | Medical devices, automation equipment | ASTM F2063 (Nitinol) |
| Superconducting Alloy | Lead, Aluminum, Tungsten | Exhibits zero electrical resistance at low temperatures | Superconducting magnets, medical imaging devices | ASTM B714 (Nb3Sn), ASTM B335 (NbTi) |
Advantages and Disadvantages of Alloys
The advantages and disadvantages of alloys vary depending on their composition and purpose, so various performance characteristics must be weighed when selecting and using alloys to meet the requirements of specific applications.
| Aspect | Advantages | Disadvantages |
| Strength and Hardness | Alloys typically offer greater strength and hardness than their constituent metals (e.g., steel is stronger than pure iron). | Some alloys may become brittle under certain conditions, limiting their use in specific environments. |
| Corrosion Resistance | Enhanced corrosion resistance is a key feature of many alloys, such as stainless steel with chromium and nickel. | The production of corrosion-resistant alloys can be expensive, increasing overall material costs. |
| Conductivity | Some alloys, like copper alloys, provide excellent electrical and thermal conductivity, crucial for electronics. | Alloy production requires precise control over composition and process, which can introduce complexity. |
| Wear Resistance | Alloys with elements like chromium, tungsten, or molybdenum are highly wear-resistant, suitable for high-friction applications. | High wear resistance might come with reduced ductility, making the material less versatile in forming processes. |
| Machinability | Adjusting alloy compositions can lead to improved machinability, reducing manufacturing challenges and costs. | Certain high-strength alloys may be difficult to machine, requiring special tools or processes. |
| Heat Resistance | Alloys like nickel-based superalloys maintain strength and stability at high temperatures, ideal for aerospace and energy industries. | Heat-resistant alloys are often expensive and may require specialized handling and processing. |
| Cost | Enhanced properties justify higher costs in critical applications where performance outweighs expense. | The overall cost of producing and using alloys can be significantly higher compared to pure metals. |
| Environmental and Health Risks | Some alloys contain toxic elements, such as cadmium or beryllium, posing environmental and health risks. | Disposal and handling of toxic alloy components require careful consideration and may incur additional costs. |
| Magnetism | Magnetic properties of some alloys, such as certain stainless steels, are advantageous in specific applications. | Unwanted magnetism in alloys may affect performance in electronic or magnetic-sensitive applications. |
Why SSM is Your Trusted Supplier of Alloy Products
The alloys supplied by SSM include carbon steel, stainless steel, various nickel alloys, aluminum alloys, etc. Get in touch with us today for a free quote and experience the difference of partnering with true experts in metal excellence.
