Dispersion strengthened materials have particulate phase...

• A. Particles are larger than in Large Particle
• B. Particulate phase is much smaller and atomic-level interactions
• C. Particles do not affect dislocations
• D. Matrix becomes brittle

Answer: (B)

Dispersion strengthening works by distributing a very fine second-phase particulate within a metal matrix. The particles are extremely small and evenly spread, so dislocations must contend with many obstacles as they move. This leads to higher strength because the dislocations either bow around these tiny particles or cut through them at interfaces, and the cumulative effect of countless interactions at the particle–matrix interfaces raises the stress needed for plastic deformation. Larger particles wouldn’t block dislocations as effectively and could even become sites for crack initiation, while saying the particles don’t affect dislocations contradicts the whole strengthening mechanism, and the matrix isn’t inherently made brittle by dispersion strengthening—it aims to keep ductility while boosting strength.