Materials

Materials are substances with inherent usefulness in the creation of products, structures, and devices. They encompass natural materials and engineered materials whose properties can be tailored for specific applications. Material science investigates how composition, microstructure, and processing affect performance across multiple length scales.

Classification commonly follows composition and structure. Metals such as steel and aluminum provide high strength and ductility. Polymers, including plastics and resins, offer light weight and versatile processing. Ceramics like porcelains and refractories exhibit high hardness and temperature stability but can be brittle. Composites combine constituents such as fibers and matrices to achieve improved strength-to-weight ratios. Glasses, ceramics-based materials, biomaterials used in medicine, and nanomaterials with unique size-dependent properties are also important groups.

Key properties govern material performance: mechanical (strength, stiffness, toughness, hardness), thermal (conductivity, thermal expansion), electrical (conductivity, dielectric behavior), and chemical (corrosion resistance, reactivity). Physical traits such as density and porosity, as well as functional properties like magnetism or optical response, are also relevant. Processing methods—casting, forming, deformation, coatings, heat treatments, and additive manufacturing—control microstructure and thus final properties.

Selection and lifecycle considerations are central to engineering practice. Designers choose materials to meet demanding requirements while considering manufacturability, reliability, and cost. Sustainability aspects include recyclability, life-cycle assessment, and the potential for reuse or substitution with lower-impact alternatives.

Standards and testing underpin material evaluation. Mechanical tests (tensile, hardness, impact), thermal analyses, spectroscopy, and microscopy characterize performance, while organizations such as ISO and ASTM publish criteria to ensure consistency and safety across industries.