MSE

• Materials Science and Engineering

  The study of the properties and applications of various materials, including metals, ceramics, polymers, and composites
• Historical Perspective of Material Science


  • Beginning of the Material Science– People started to make tools from stone, Start of the Stone Age about two million years ago
  • Five thousand years ago introduce Bronze Age
  • The Iron Age began about 3000 years ago and continues today
  • Age of Advanced materials: throughout the Iron Age, many new types of materials have been introduced (ceramic, semiconductors, polymers, composites)
• Classification of Materials


  • Metals
  • Ceramics
  • Polymers
  • Composites
• Metals


  Materials composed of one or more metallic elements (such as iron, aluminum, copper, titanium, gold, and nickel), and often also nonmetallic elements (for example, carbon, nitrogen, and oxygen) in relatively small amounts. Atoms in metals and their alloys are arranged in a very orderly manner.
• Ceramics

  Compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. Ceramic materials are relatively stiff and strong—stiffnesses and strengths are comparable to those of the metals.
• Polymers


  Soft, pliable, low strength, low density, thermal & electrical insulators, and optically translucent or transparent. Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements (O, N, and Si).
• Composed of two (or more) individual materials, which come from the categories (metals, ceramics, and polymers). Composites are made of different materials in intimate contact (example: fiberglass, concrete, wood) to achieve specific properties.

  Composed of two (or more) individual materials, which come from the categories (metals, ceramics, and polymers). Composites are made of different materials in intimate contact (example: fiberglass, concrete, wood) to achieve specific properties.
• Design of materials having specific desired characteristics directly from our knowledge of atomic structure. The emerging new materials are: Miniaturization: Engineered Nanostructured Materials (ENM), with a microstructure that has length scales between 1 and 100 nanometers with unusual properties. Electronic components, materials for quantum computing. Smart materials: airplane wings that deice themselves, buildings that stabilize themselves in earthquakes. Environment-friendly materials: biodegradable or photodegradable plastics, advances in nuclear waste processing, etc.

  
• Crystalline solids


  A solid that contains a regular and repeating atomic or molecular arrangement over large atomic distances (long-range order). Examples are metals, ceramics, and some polymers.
• Non-crystalline Solid


  Also termed as "amorphous" or "vitreous," is a solid without long-range ordering atoms or molecules. Examples are some ceramics and most polymers.
• Types of solid materials

  • Atomic solids
  • Molecular solids
  • Ionic solids
  • Metallic solids
  • Network covalent solids
• Atomic solids


  Individual atoms that are held together by dispersion forces. Their melting and boiling points and heats of vaporization and fusion are all very low, rising smoothly with increasing molar mass. Examples are solid noble gases.
• Molecular solids


  Individual molecules occupy the lattice points. Non-polar molecules are held together by dispersion forces, while polar molecules are held together by dipole-dipole forces and H-bonding. Molecular solids have higher melting points than the atomic solids (noble gases).
• Ionic solids


  The unit cell contains particles with whole, rather than partial, charges. Ionic solids typically have high melting points and low electrical conductivities. Ionic compounds are hard because only a strong external force can change the relative positions of many trillions of interacting ions.
• Metallic solids


  Powerful metallic bonding forces hold individual atoms together. The properties of metals—high electrical and thermal conductivity, luster, and malleability—result from the presence of delocalized electrons. Metals have a wide range of melting points and hardnesses, which are related to the packing efficiency of the crystal structure and the number of valence electrons available for bonding.
• Network covalent solids


  Strong covalent bonds link the atoms together throughout the solid. All these substances have extremely high melting and boiling points, but their conductivity and hardness depend on the details of their bonding.
• Amorphous solids


  Non-crystalline solids that have small, somewhat ordered regions connected by large disordered regions. Charcoal, rubber, and glass are some familiar examples.

  
• Crystal Structure


  The manner in which atoms, ions or molecules are spatially arranged. Lattice means a three-dimensional array of points coinciding with atom position (or sphere centers). Unit cell is the basic structural unit or building block of the crystal structure and defines the crystal structure by virtue of its geometry and the atom positions within.

  
• Crystalline imperfections are lattice irregularities having one or more of its dimensions on the order of an atomic diameter. Point Defects associated with one or two atomic positions include vacancies (a vacant lattice site or missing atom) and interstitials (an atom positioned in an interstitial site between the matrix atoms).
• 1. ray diffraction


  The scattering of X rays by the units of a crystalline solid. The scattering, or diffraction, patterns produced are used to deduce the arrangement of particles in the solid lattice.