Exfoliation is associated with which phenomenon in metals?

• A. Erosion by chemicals
• B. Delamination of grain boundaries
• C. Surface oxidation
• D. Pitting

Answer: (B)

Exfoliation in metals is the peeling away of thin layers from the surface along the grain structure. This happens because grain boundaries act as easier pathways for corrosion, so layers detach as corrosion products or oxides build up and push the layers apart. It’s a form of intergranular corrosion, effectively a delamination along grain boundaries that produces sheet-like pieces peeling off parallel to the surface. This is different from a uniform loss by chemical erosion, localized pits, or simple surface oxidation, which is why the idea of layers separating along grain boundaries best describes exfoliation.