Materials Science: Key Properties, Classes, and Strengthening Methods

Design-limiting properties

Properties that constrain material choice (e.g., density, stiffness, cost)

Classes of materials

Metals, polymers, ceramics, composites, hybrids

Elastic modulus

Determined by atomic bond strength

Density

Determined by atomic/molecular packing

Yield strength

Stress at which plastic deformation begins

Ductility

Ability to deform plastically before fracture

Hardness

Resistance to localized plastic deformation

Ways to strengthen metals

Grain refinement, alloying, work hardening, heat treatment

Ashby chart

Graphical tool to compare material properties

Stress

Force per unit area

Strain

Deformation per unit length

Toughness

Energy absorbed before fracture (area under stress-strain curve)

Plastic work

Work done during plastic deformation