In a fiber-reinforced composite, what is the dispersed phase?

• A. The matrix itself.
• B. The interface layer.
• C. The dispersed phase is the material embedded within the matrix.
• D. The voids within the material.

Answer: (C)

In a fiber-reinforced composite, phases are split into a continuous matrix and a dispersed reinforcement. The dispersed phase is the reinforcing material embedded within the matrix—the fibers themselves (such as carbon, glass, or ceramic fibers) scattered through and surrounded by the matrix. These fibers carry a large portion of the load and provide high stiffness along their length, while the matrix binds the fibers, transfers stress, and protects them. The boundary layer between fiber and matrix is the interface, and any voids are defects rather than a designed dispersed phase. So the dispersed phase is the reinforcing material embedded within the matrix.