What do we call materials that have uniform composition and elastic properties in all directions?

The term used for materials that exhibit uniform composition and elastic properties in all directions is isotropic materials. Isotropic materials are characterized by having the same mechanical properties regardless of the direction in which they are measured. This means that their behavior under stress, strain, and other mechanical forces is consistent, regardless of the orientation of the applied load.

While homogeneous materials also refer to a uniform composition, it does not inherently imply uniform elastic properties in all directions. Homogeneity pertains to the material being the same throughout its volume, but the arising properties under mechanical loading could vary depending on the material's structure and composition.

In contrast, composite materials refer to those made from two or more constituent materials with significantly different physical or chemical properties, ensuring that the resulting material has characteristics different from the individual components. Designed materials typically are engineered for specific applications but do not specifically denote uniform behavior in all directions.

Thus, the term that precisely describes materials with both uniform composition and elastic properties in all directions is isotropic materials.