What is the Difference Between Alloy and Intermetallic Compound

The key difference between alloy and intermetallic compound is that alloys contain metallic components and nonmetallic components, whereas intermetallic compounds contain metallic or semi-metallic components.

An alloy is a metallic substance that contains at least one metal element along with other elements. Intermetallic compounds are materials containing solid phases involving two or more metallic or semi-metallic elements arranged in an ordered structure.

CONTENTS

1. Overview and Key Difference
2. What is  an Alloy 
3. What is an Intermetallic Compound
4. Alloy vs Intermetallic Compound in Tabular Form
5. Summary – Alloy vs Intermetallic Compound

What is an Alloy?

Alloys are metallic substances consisting of at least one metal element along with other elements. These substances have enhanced properties when compared to the properties of every single element they are made of. We can obtain the properties of alloys by mixing chemical elements in different percentages. Therefore, they give the desired properties by mixing different metals and elements in different amounts. Almost all alloys have a lustre due to the presence of the metal component. Alloys are also able to conduct electricity due to the presence of a metal component.

Classification of Alloys

We can classify alloys in different ways. For example, they can be either homogenous or heterogeneous. Homogenous alloys have components distributed throughout the material uniformly. Heterogeneous alloys, on the other hand, have components distributed in an unorganized manner.

Furthermore, there are substitutional and interstitial alloys. Substitutional alloys are metal alloys formed from substituting one metal atom for another metal atom of similar size. Interstitial alloys are metal alloys formed by inserting smaller atoms into holes of the metal lattice.

What is Intermetallic Compound?

Intermetallic compounds are materials containing solid phases involving two or more metallic or semi-metallic elements arranged in an ordered structure. They are also named intermetallic or intermetallic alloys. Often these compounds have a well-defined and fixed stoichiometry. Generally, intermetallic compounds are hard and brittle, having high-temperature mechanical properties. We can classify these compounds as stoichiometric and non-stoichiometric intermetallic compounds.

Properties of Intermetallic Compounds

When considering the properties and applications of these compounds, they generally have high melting points and are brittle at room temperature. There can be cleavage or intergranular fracture modes of intermetallic compounds because of the limited independent slip systems that are needed for plastic deformation. However, there can be ductile fracture modes of intermetallic compounds as well. This ductility can be improved in these compounds through alloying other materials such as boron, which can improve grain boundary cohesion.

Some common examples of intermetallic compounds include magnetic materials such as alnico, sendust, and Permendur, superconductors such as A 15 phases and niobium-tin, shape memory alloys, etc. The intermetallic compounds we can find from history include Roman yellow brass, Chinese high tin bronze and type metal, SbSn.

What is the Difference Between Alloy and Intermetallic Compound?

Alloys and intermetallic compounds are industrially important compounds. The key difference between alloy and intermetallic compound is that alloys contain metallic components and nonmetallic components, whereas intermetallic compounds contain metallic or semi-metallic components. Bronze, brass, steel, wrought iron, cast iron, and stainless steel are examples of alloys whereas magnetic materials such as alnico, sendust, and Permendur, superconductors such as A 15 phases and niobium-tin, shape memory alloys, etc. are intermetallic compounds.

The below infographic lists the differences between alloy and intermetallic compound in tabular form.

Summary – Alloy vs Intermetallic Compound

Alloys and intermetallic compounds are industrially important compounds. The key difference between alloy and intermetallic compound is that alloys contain metallic components and nonmetallic components, whereas intermetallic compounds contain metallic or semi-metallic components.

Reference:

1. “Intermetallic Compound.” ScienceDirect Topics.

Image Courtesy:

1. “Bull’s head ornament for a lyre MET DP260070” donated to Wikimedia Commons as part of a project by the Metropolitan Museum of Art. See the Image and Data Resources Open Access Policy (CC0)
2. “Cr11Ge19 crystals” By Hui Han et al. – Nature.com (CC BY 4.0) via Commons Wikimedia