Difference Between Alloy and Composite

Main Difference – Alloy vs Composite

Alloys and composites are mixtures of elements. The main difference between alloy and composite is that alloy has at least one metal in its composition whereas composites do not have metal components. Both alloys and composites indicate different characteristics than their starting materials. Although both of them are composed of at least two types of elements, they have several distinct properties which make them different from each other.

Key Areas Covered

1. What is an Alloy
      – Definition, Composition, Properties and Uses
2. What is a Composite
       – Definition, Composition, Properties and Uses
3. What is the difference between Alloy and Composite
      – Comparison of Key Differences

Key Terms: Alloy, Brass, Bronze, Composite, Luster, Metal, Mineral, Steel

What is an Alloy

Alloys are metallic compounds. An alloy contains at least one metal element along with other elements. Alloys have improved properties when compared to properties of each single element they are made of. These properties are obtained by mixing elements in different percentages. Therefore, the desired properties can be obtained by mixing different metals and elements in different amounts. Alloys may be homogenous or heterogeneous. Almost all alloys have a luster due to the presence of the metal component. Alloys are also able to conduct electricity due to the presence of a metal component.

Common Alloys

Name of Alloy	Composition	Properties	Uses
Steel	Mainly iron, carbon and other elements such as phosphorous or sulfur.	Strength, toughness, durability, weldability.	Used as building material
Brass	Mainly copper, zinc sometimes with aluminium or lead.	Malleability, softness, low friction	Decoration purposes
Bronze	Mainly copper, tin sometimes with arsenic, aluminium, phosphorous.	Corrosion resistance, hard and brittle	Ship and boat fittings
Duralumin	Copper, manganese, magnesium and sometimes silicon.	Light, strong	To make airplane body

Figure 01: A musical instrument made of brass

What is a Composite?

A composite is also a mixture of two or more elements, but it does not contain metal components. Unlike alloys, composites are always heterogeneous. Most composites are found naturally while some composites are synthetic. Composites are made out of components which have significantly different physical properties. Wood is a natural composite and concrete is a synthetic composite. Some common composites and their properties are shown below.

Common Composites

Name of the composite	composition	Properties
Wood	Cellulose fibers and lignin	Strong
Bones of human body	Calcium phosphate and collagen	Hard, but brittle
Fiberglass	Plastic matrix and glass	Suitable for boat hulls and car bodies due to light weight
Concrete	Stones, cement, and sand	Good compressive strength

Figure 2: Benches made of Wood

Definition

Alloy: Alloy is a mixture of two or more metallic components with other elements.

Composite: Composite is a mixture of non-metallic components.

Composition

Alloy: Alloys always have at least one metal element.

Composite: Composites do not have any metal atoms.

Arrangement

Alloy: Alloys can be either homogeneous or heterogeneous.

Composite: Composites are always heterogeneous.

Appearance

Alloy: Alloys have a luster due to the presence of a metal.

Composite: Composites do not have a luster.

Electrical Conductance

Alloy: Almost all the alloys can conduct electricity due to the presence of a metal.

Composite: Polymeric composites can conduct electricity whereas other composites cannot.

Conclusion

Both alloys and composites are mixtures of elements. Alloys can be found naturally although they are very rare. Composites occur naturally almost everywhere. The main difference between alloy and composite is that alloy has at least one metal in its composition whereas composites do not have metal components.

References:

1.Johnson, Todd. “What Is a Composite Material?” ThoughtCo. N.p., n.d. Web. Available here. 15 June 2017.
2.Shiwakoti, Ritesh. “Metals and Alloy.” LinkedIn SlideShare. N.p., 31 Oct. 2014. Web. Available here. 15 June 2017.

Image Courtesy:

1. “Bench Wooden Bench Wood Click Forest Seat Out” (CC0) via Max Pixel
2. “Valves Rotary Valves Tuba Stimmzug Brass Instrument” (CC0) via Max Pixel