Material Science Lecture 1

Materials Science

• Materials science involves investigating the relationships between the structures and properties of materials.
• The role of a materials scientist is to develop or synthesize new materials.

Materials Engineering

• Materials engineering involves designing or engineering the structure of a material to produce a predetermined set of properties.
• A materials engineer creates new products or systems using existing materials and/or develops techniques for processing materials.

Material Evolution

• Material science involves investigating the relationships between the structures and properties of materials.
• The role of a materials scientist is to develop or synthesize new materials.

Structure, Properties, and Performance

• The structure of a material relates to the arrangement of its internal components.
• Subatomic structure involves electrons within individual atoms and interactions with their nuclei.
• Microscopic structure refers to the organization of atoms or molecules relative to one another.
• Macroscopic structure refers to structural elements that can be viewed with the naked eye.
• Properties relate to the material's shape and size.
• Performance is the function of its properties.

Properties of Materials

• Virtually all important properties of solid materials can be grouped into six categories:
  • Mechanical properties (e.g., elastic modulus, strength, and toughness)
  • Electrical properties (e.g., electrical conductivity and dielectric constant)
  • Thermal properties (e.g., heat conduction efficiency)
  • Magnetic properties (e.g., response to a magnetic field)
  • Optical properties (e.g., index of refraction and reflectivity)
  • Deteriorative characteristics (e.g., chemical reactivity, corrosion)

Classification of Materials

• Solid materials can be grouped into three basic categories: metals, ceramics, and polymers.
• Composites are engineered combinations of two or more different materials.
• Advanced materials are used in high-technology applications (e.g., semiconductors, biomaterials, smart materials, and nanoengineered materials).

Metals

• Metals are composed of one or more metallic elements and often nonmetallic elements.
• Metallic materials have large numbers of nonlocalized electrons.
• Properties of metals:
  • Good conductors of electricity and heat
  • Not transparent to visible light
  • Lustrous appearance

Polymers

• Polymers include familiar plastic and rubber materials.
• They are organic compounds based on carbon, hydrogen, and other nonmetallic elements.
• Properties of polymers:
  • Good electrical insulation
  • Heat insulation
  • High flexibility
  • Light weight
  • Low strength

Ceramics

• Ceramics are compounds between metallic and nonmetallic elements.
• Properties of ceramics:
  • Insulating heat and electricity
  • High temperature resistance
  • More durable in a toxic environment than metal and polymers
  • Strong but fragile

Composites

• A composite is composed of two or more individual materials.
• Design goal of a composite is to achieve a combination of properties not displayed by any single material.
• Properties of composites:
  • Combination of properties from individual materials
  • Incorporating the best characteristics of each component material

Advanced Materials

• Advanced materials are used in high-tech applications.
• Examples include:
  • Semiconductors (having electrical conductivities intermediate between those of conductors and insulators)
  • Biomaterials
  • Smart materials
  • Nanoengineered materials