What defines a composite material?

A composite material is defined as a combination of two or more different materials that, when combined, produce a material with superior mechanical properties than the individual components would exhibit on their own. This enhanced performance comes from the synergistic effects of the different materials, allowing composites to be tailored for specific applications by optimizing stiffness, strength, lightweight characteristics, and other desirable properties.

In composite materials, one material typically acts as a matrix, providing support and binding the other material, which often acts as a reinforcement and enhances strength or other mechanical attributes. This unique combination is what allows composites to excel in various fields, such as aerospace, automotive, and marine applications, making them highly favorable for designs requiring high strength-to-weight ratios.

The other options do not accurately capture the defining characteristics of composites. A composite is not a single substance with uniform properties or limited to natural resources, nor is it strictly defined by a material's ability to change form under heat and pressure. These characteristics pertain to different material types or behaviors and do not encompass the fundamental nature of composite materials.