Question

Magnetic permeability of iron is increased by:

• A. Purification
• B. Decarburising
• C. Alternating heating and cooling
• D. Alloying with cobalt

Hint:

To enhance the magnetic permeability of iron, alloying with \textbf{cobalt} is a proven method due to its high magnetic saturation and thermal stability.

Answer 1

The Correct Option is D

Step 1: Magnetic Permeability Definition
Magnetic permeability (\( \mu \)) is a measure of how easily a material can support the formation of a magnetic field within itself. Step 2: Role of Cobalt in Iron
- Alloying iron with cobalt (Co) significantly increases its magnetic permeability. - Cobalt enhances the magnetic moment and reduces hysteresis losses. - It stabilizes the magnetic domain structure and improves the overall magnetic response of the alloy. Step 3: Evaluation of Other Options
- Purification: Improves electrical conductivity, but effect on permeability is limited. - Decarburising: Reduces carbon content but doesn't enhance permeability as effectively. - Alternating heating and cooling (annealing): Improves grain structure but has a smaller impact compared to alloying with cobalt. Conclusion: The most effective way to increase the magnetic permeability of iron is by alloying it with cobalt.