Question

Tungsten carbide is an example of: (a) Passive solid solution (b) Interstitial solid solution (c) Sandwich solid solution (d) Substitutional solid solution

Short answer

Tungsten carbide is an example of an interstitial solid solution.

Step-by-step solution

Understand Solid Solutions

Solid solutions are homogeneous mixtures of two or more elements, where the atomic properties influence how these elements combine. There are different types of solid solutions based on the arrangement and size of atoms involved.

Define Interstitial Solid Solutions

Interstitial solid solutions occur when smaller atoms like carbon fit into the spaces (interstices) between larger metal atoms in a crystal lattice. This type of solution allows the smaller atoms to be accommodated within the spaces of the host metal’s structure.

Identify the Structure of Tungsten Carbide

Tungsten carbide is a compound formed by the combination of tungsten and carbon atoms. The carbon atoms in tungsten carbide fit into the interstitial sites of tungsten's crystal lattice.

Conclusion Based on Observation

Due to the incorporation of smaller carbon atoms into the interstitial spaces of tungsten, tungsten carbide is classified as an interstitial solid solution.

Key concepts

Interstitial Solid Solutions

In the world of chemistry and material science, interstitial solid solutions play a vital role. They form when tiny atoms, like carbon or nitrogen, slip into the spaces between larger metal atoms. Such spaces in a crystal structure are known as interstices. These smaller atoms don't replace any of the metal atoms but rather nestle into the gaps.
These types of solutions are commonly found in hard, durable materials like steel. The interstices are typically small, so only a limited number of atoms can fit there. The introduction of smaller atoms into the metal's structure strengthens it solidly. This is because these atoms block movement in the crystal lattice, making the material firmer.
Understanding interstitial solid solutions can help in engineering applications where strength, durability, and hardness are critical.

Crystal Lattice

A crystal lattice can be thought of as the skeleton of a solid material. It is a three-dimensional arrangement of atoms, ions, or molecules. They repeat in a pattern at regular intervals, maintaining structural stability.
Every crystal lattice has a unique geometry, which greatly impacts the physical properties of the material, such as its strength, elasticity, and conductivity. These lattices bear both the weight and the chemical properties defined by the element's atomic arrangement.
The spaces between the atoms in a lattice provide an opportunity for smaller atoms to fit in, as in interstitial solid solutions. Therefore, understanding the crystal lattice is crucial when studying material properties and manipulating them for specific uses.

Tungsten Carbide

Tungsten carbide is a fascinating material that offers a unique blend of properties, such as extreme hardness and resistance to wear. It’s often used in industrial applications like cutting tools and abrasives.
In the structure of tungsten carbide, the carbon atoms find their place in the interstitial sites of tungsten's crystal lattice. The positioning of these atoms significantly contributes to the material's high level of hardness and strength.

• It comprises tungsten atoms with small carbon atoms fitting into the interstitial spaces.
• The interaction between carbon and tungsten atoms prevents dislocations, which contributes to its hardness.

Thus, tungsten carbide is an example of an interstitial solid solution, where the small carbon atoms strengthen the tungsten matrix, resulting in a material highly prized for its durability.