Question

Plastic deformation in metals at room temperature is primarily due to:

• A. Slip
• B. Twisting
• C. Cracking
• D. Vaporization

Hint:

When metals bend or stretch permanently, it’s because of layers of atoms slipping past one another. Always associate plastic deformation with slip, especially in metals.

Answer 1

The Correct Option is A

Plastic deformation is the permanent change in shape of a material when a force is applied beyond its elastic limit. In metals, this phenomenon is most commonly caused by a mechanism called slip.
What is Slip?

• Slip is the movement of layers of atoms over one another along specific crystallographic planes called slip planes.
• These movements occur due to applied stress and typically happen along planes with the highest atomic density, where resistance to movement is minimal.
• Slip allows metals to bend or stretch without breaking, which is why metals are ductile and malleable.
• This mechanism is aided by the presence of dislocations (defects in the crystal structure), which reduce the energy needed for atoms to move.

Why the Other Options Are Incorrect:

• (B) Twisting: Refers to a mode of deformation, not a mechanism at the atomic level.
• (C) Cracking: Indicates fracture or failure, not plastic deformation.
• (D) Vaporization: Involves a change of state from solid to gas, which is not relevant at room temperature or under normal deformation conditions.

Therefore, the primary cause of plastic deformation in metals at room temperature is slip.