MSE

• Materials science and engineering (MSE)


  An interdisciplinary field concerned with inventing new materials and improving previously known materials by developing a deeper understanding of the microstructure-composition-synthesis-processing relationships
• Composition


  The chemical make-up of a material
• Structure


  A description of the arrangement of atoms, as seen at different levels of detail
• Materials scientists and engineers deal with the development, synthesis, processing, and manufacturing of materials
• Synthesis


  How materials are made from naturally occurring or man-made chemicals
• Processing


  How materials are shaped into useful components
• One of the most important functions of materials scientists and engineers is to establish the relationships between the properties of a material and its performance
• In materials science, the emphasis is on the underlying relationships between synthesis and processing, structure, and properties of materials
• In materials engineering, the focus is on how to translate or transform materials into a useful device or structure
• The structure of a material significantly influences properties, even if the overall composition remains unchanged
• Microstructure changes can be observed with an optical microscope, and understanding these changes at a micrometer level is key to controlling a material's properties
• The microstructure-synthesis, processing-composition, and performance-to-cost ratio are all interconnected in the materials science and engineering tetrahedron
• Ceramic superconductors were discovered in 1986, which was unexpected as ceramics usually do not conduct electricity
• Developing ceramic superconductors


  1. Discovery of superconducting behavior

  2. Determining how to make the materials better (higher temperature superconductivity, ability to transport large currents)

  3. Developing controlled synthesis of ultrafine powders or thin films

  4. Finding ways to make long superconducting wires
• Metals and Alloys


  • Copper (electrical conductor wire)
  • Gray cast iron (automobile engine blocks)
  • Alloy steels (wrenches, automobile chassis)
• Ceramics and Glasses


  • SiO2-Na2O-CaO (window glass, soda-lime glass)
  • Al2O3, MgO, SiO2 (refractories)
  • Barium titanate (capacitors)
  • Silica (optical fibers)
• Semiconductors


  • Silicon (transistors, integrated circuits)
  • GaAs (optoelectronics)
• Metals and Alloys


  • Good electrical and thermal conductivity
  • High strength, stiffness, ductility, and shock resistance
  • Useful for structural or load-bearing applications
• Ceramics


  • Inorganic crystalline materials
  • Brittle due to porosity
  • Strong, hard, but very brittle
• Polymers


  • Organic materials produced by polymerization
  • Good electrical resistivity and thermal insulation
  • Lower strength but good strength-to-weight ratio
  • Thermoplastics are ductile and formable, thermosets are stronger but more brittle
• Semiconductors


  • Electrical conductivity between insulators and conductors
  • Enabled the information age
  • Conductivity controlled for use in electronic devices
• Composites


  • Blend properties of different materials
  • Can produce lightweight, strong, ductile, high-temperature-resistant materials
• Geckos can cling to surfaces due to van der Waals forces between microscopic hairs on their toe pads and the surface
• Understanding interatomic bonding can explain material properties, like the differences between graphite and diamond
• Bohr atomic model


  Electrons revolve around the atomic nucleus in discrete orbitals
• Wave-mechanical model


  Electron position is described by a probability distribution or electron cloud
• Schrödinger's atomic model


  Electrons exhibit both wave-like and particle-like characteristics
• Pauli exclusion principle


  Each electron state can hold no more than two electrons with opposite spins
• Valence electrons


  Electrons that occupy the outermost shell and participate in bonding
• Titanium


  • High strength-to-weight ratio
  • Used to alloy with other metals to produce strong, lightweight alloys
• Pauli exclusion principle


  Quantum-mechanical concept that stipulates each electron state can hold no more than two electrons with opposite spins
• s, p, d, and f subshells may each accommodate, respectively, a total of 2, 6, 10, and 14 electrons
• Valence electrons


  Electrons that occupy the outermost shell, extremely important as they participate in bonding between atoms
• Many of the physical and chemical properties of solids are based on these valence electrons
• Titanium


  • High strength-to-weight ratio, twice as strong as aluminum but only 60% heavier, as strong as steel but weighs much less
  • Used to alloy with different metals to produce strong and lightweight alloys
  • Resistant to corrosion, especially useful in sea water applications
• Tungsten


  • One of the toughest things found in nature, super dense and almost impossible to melt
  • Used in filaments in incandescent light bulbs, electric contacts, arc-welding electrodes, and alloys to impart great strength
• Copper


  • Used mostly in its metal form, about 60% used for electrical wiring and cable due to its electrical conductivity, ductility, corrosion resistance, low thermal expansion, and tensile strength
  • Also used in plumbing, roofing, industrial machinery, integrated circuits, cookware, coins, and electric motors
  • Around 5% used to make metal alloys like brass and bronze
• Silver


  • Highest electrical conductivity of all elements, highest thermal conductivity of metals
  • Used since ancient times for jewelry and silverware, today mostly in alloy form
  • Used in electronics industry due to excellent electrical conductivity, also in long-life batteries, mirrors, dental fillings, musical instruments, and nuclear reactors
• Gold


  • Most malleable and ductile of metals, excellent conductor of electricity and heat, highly resistant to corrosion and rust
• Platinum


  • Used as currency and investment, in jewelry, as a catalyst in chemical reactions, in alloys for special metals, super strong magnets, medical instruments, and dental work