INTRODUCTION - MATSCI

• Materials science


  Involves investigating the relationships that exist between the structures and properties of materials
• Materials Engineering


  On the basis of structure–property correlations, designing or engineering the structure of a material to produce a predetermined set of properties
• Role of a materials scientist


  Develop or synthesize new materials
• Role of a materials engineer


  Create new products or systems using existing materials, and/or to develop techniques for processing materials
• Structure


  Usually relates to the arrangement of a material's internal components
• Property


  A material trait in terms of the kind and magnitude of response to a specific imposed stimulus
• Categories of solid materials

  • Mechanical
  • Electrical
  • Thermal
  • Magnetic
  • Optical
  • Deteriorative
• Materials science and engineering

  1. Processing

  2. Structure

  3. Properties

  4. Performance
• Structure of a material


  Depends on how it is processed
• Material's performance


  Is a function of its properties
• Photograph of three thin disk specimens of aluminum oxide

  • Demonstrates their differences in light-transmittance characteristics
• Criteria for selecting the right material

  • In-service conditions
  • Deterioration of material properties that may occur during service operation
  • Economics
• Classification of materials


  • Metals
  • Ceramics
  • Polymers
  • Composites
  • Biomaterials
  • Advanced materials (semiconductors, biomaterials, smart materials, and nanoengineered materials)
• Metals


  • Composed of one or more metallic elements, and often also nonmetallic elements
  • Relatively stiff and strong, yet are ductile and resistant to fracture
  • Extremely good conductors of electricity and heat, and are not transparent to visible light
  • Have a lustrous appearance
  • Some have desirable magnetic properties
• Ceramics


  • Compounds between metallic and nonmetallic elements, most frequently oxides, nitrides, and carbides
  • Relatively stiff and typically very hard
  • Extremely brittle (lack ductility)
  • Insulative to the passage of heat and electricity
  • Resistant to high temperatures and harsh environments than metals and polymers
  • May be transparent, translucent, or opaque
• Polymers


  • Include the familiar plastic and rubber materials
  • Have very large molecular structures, with a backbone of carbon atoms
  • Typically have low densities
  • Not as stiff nor as strong as other materials
  • Extremely ductile and pliable, easily formed into complex shapes
  • Relatively inert chemically and unreactive in a large number of environments
  • Tend to soften and/or decompose at modest temperatures
  • Have low electrical conductivities and are nonmagnetic
• Composites


  • Composed of two (or more) individual materials, from metals, ceramics, and polymers
  • Combine properties not displayed by any single material, and incorporate the best characteristics of each component material
  • One example is fiberglass, with small glass fibers embedded within a polymeric material
• Advanced materials


  Materials utilized in high-technology applications
• Semiconductors


  • Have electrical properties intermediate between conductors and insulators
  • Electrical characteristics are extremely sensitive to the presence of minute concentrations of impurity atoms
  • Have made possible the advent of integrated circuitry that has revolutionized electronics and computing
• Biomaterials


  • Employed in components implanted into the human body for replacement of diseased or damaged body parts
  • Must not produce toxic substances and must be compatible with body tissues
• Smart materials


  • Able to sense changes in their environments and then respond to these changes in predetermined manners
  • Components include a sensor that detects an input signal, and an actuator that performs a responsive and adaptive function
• Nanoengineered materials


  The ability to carefully arrange atoms provides opportunities to develop mechanical, electrical, magnetic, and other properties, using a "bottom-up" approach
• Consideration of the environmental impact of materials production is a modern materials need
• New high strength, low-density structural materials remain to be developed, as well as materials that have higher-temperature capabilities, for use in engine components
• Finding new, economical sources of energy and using present resources more efficiently is a modern materials need
• Improving our ability to control air and water pollution is a modern materials need