What term describes the ability of a material to undergo permanent shape change?

• A. Elasticity
• B. Plasticity
• C. Ductility
• D. Malleability

Answer: (B)

Permanent deformation comes from plasticity—the material’s ability to undergo shape change that remains after the applied load is removed. When stress pushes a material beyond its elastic limit, its internal structure rearranges (dislocations move, grains realign), and the deformation isn’t recovered, so the new shape stays. Elasticity would only cause temporary deformation that springs back when the load is removed. Ductility and malleability describe specifics of plastic behavior under different loading: ductility is about how far a material can extend or stretch in tension before fracture, while malleability is about deforming under compression. But the broad term for permanent shape change is plasticity.