Metals are fundamental elements, but by combining them, we create even more versatile materials called alloys. This article delves into the properties of each and explores the key difference between metal and alloy.
What is the difference between metal and alloy? Metal is an elemental substance made up of one type of atom, whereas an alloy is a mixture of two or more metals.
Key Areas Covered
1. What is a Metal
– Definition, Features
2. What is an Alloy
– Definition, Features
3. Similarities Between Metal and Alloy
– Outline of Common Features
4. Difference Between Metal and Alloy
– Comparison of Key Differences
5. FAQ: Metal and Alloy
– Answers to Frequently Asked Questions
Key Terms
Alloy, Metal
What is a Metal
Metal is an elemental substance made up of one type of atom. The behaviour of a metal is determined by the nature of atoms within the metal. The structure of a metal lattice consists of some valence electrons freely moving in the lattice. This delocalized electron cloud is responsible for certain properties of the metal such as high electrical conductivity, thermal conductivity luster, and malleability.
The bond between the metal atoms within a metal is called a metallic bond. Even the arrangement of atoms within a metal is responsible for the metal’s properties, such as its electronic and chemical behaviour.
Some examples of metals are gold, silver, iron, and copper. One of the major properties of metal is its ability to conduct electricity. This property is why metals like copper and aluminium are extensively used in wiring and electrical components. Additionally, metals are malleable and ductile, allowing them to be shaped and formed into various structures and products.
Metals undergo several types of reactions, such as oxidation, reduction, and complexation reactions, which can be seen in industrial and biological systems. For example, the corrosion of metals due to exposure to oxygen and moisture is a significant concern in engineering, while the role of transition metals as cofactors in enzyme catalysis is essential for life.
Another property of metals is their high thermal conductivity. This property is used in instances where heat transfer is critical, such as in heat sinks for electronics and in cooking utensils. Their strength is even used in the construction industry, such as in buildings, vehicles, and bridges.
What is an Alloy
Alloys are a mixture of two or more metals. Their unique characteristics and properties depend on the nature of the mixture of the metals within the alloy. At the atomic level, metals consist of closely packed atoms arranged in a regular, repeating pattern called a crystal lattice. When different metals are mixed to form an alloy, their atoms integrate into the existing lattice structure, either replacing atoms of the primary metal or occupying spaces between them.
Solid solution strengthening is a concept in alloy chemistry where the presence of smaller atoms in the lattice disrupts the orderly arrangement of the larger atoms, making it more difficult for them to slide past one another. This gives strength and hardness to the alloy, which improves its mechanical properties.
Some of the common properties of alloys include increased corrosion resistance, magnetism, and electrical conductivity. These properties depend on the composition of each metal in the mixture of alloys. For example, stainless steel, an alloy of iron, chromium, and nickel, is highly resistant to rust due to the formation of a protective chromium oxide layer on its surface.
Furthermore, the phase diagram of an alloy illustrates how its composition and temperature affect its microstructure and properties. Understanding phase diagrams is essential for controlling the manufacturing process and tailoring alloys to meet specific requirements.
Similarities Between Metal and Alloy
- Due to the presence of free electrons, both metals and alloys have good electrical and thermal conductivity.
- Both metals and alloys exhibit a shiny metallic luster.
- They can be shaped and formed through processes like hammering, rolling, and extrusion.
Difference Between Metal and Alloy
Definition
- Metals are pure chemical elements, while alloys are mixtures of two or more elements, including at least one metal.
Creation
- Metals are found naturally in the earth as elements and can be extracted from ores. Alloys are created by combining different elements, either metals or a metal and a non-metal, to achieve desired properties.
Melting Point
- Alloys typically have a lower melting point compared to pure metals due to the presence of different elements that can disrupt the metallic bonds.
Nature
- Metals are usually homogeneous in structure, whereas alloys can have varying degrees of homogeneity depending on the mixing process.
Reactions
- While metals often easily react with water and air, alloys are made for increased resistance to water and air (corrosion and oxidation).
Examples
- Iron, gold, copper, tin, and aluminum are examples of metals, while steel (iron and carbon), brass (copper and zinc), and bronze (copper and tin) are examples of alloys.
Conclusion
Metals and alloys both conduct electricity, have a luster and can be shaped easily. However, there is a distinct difference between metal and alloy in terms of their composition and properties. Metals are made of single-element substances with specific atomic structures, while alloys are mixtures of two or more metals, often offering improved strength and resistance to corrosion.
FAQ: Metal and Alloy
1. What is the strongest alloy on earth?
An alloy of chromium, cobalt, and nickel (CrCoNi) is the toughest material ever tested, and its characteristics could make it useful in the construction of aircraft or spacecraft.
2. Is alloy stronger than gold?
Gold alloys generally have a greater strength than pure gold. They are also more durable than pure gold metal.
3. Is every metal an alloy?
No, not every metal is an alloy. A metal can be in its pure form, consisting of a single element like gold or iron. An alloy, however, is a mixture of two or more elements, where at least one of them is a metal.
4. Is titanium an alloy?
There are six grades of pure titanium (grades 1,2,3,4,7, and 11) and 4 varieties of titanium alloys. Titanium alloys typically contain traces of aluminium, molybdenum, vanadium, niobium, tantalum, zirconium, manganese, iron, chromium, cobalt, nickel, and copper.
5. Are alloys better than metals?
Alloys can be better than pure metals in some applications because they often offer improved properties such as increased strength and corrosion resistance. However, pure metals may still be preferable in cases where their specific properties, such as high electrical conductivity or malleability, are needed.
Reference:
1. “Metal – Chemistry.” Encyclopedia Britannica.
2. “Alloy.” Encyclopedia Britannica.
Image Courtesy:
1. “Iron electrolytic and 1cm3 cube” By Alchemist-hp (talk) (www.pse-mendelejew.de) – Own work (FAL) via Commons Wikimedia
2. “Alloy atomic arrangements showing the different types” By Hbf878 – Own work (CC0) via Commons Wikimedia
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