Materials Science

Stuff – The Materials the World is Made of by Ivan Amato

Discipline of Materials Science & Engineering Utilize Principles of Physics and Chemistry to Understand and Advance Knowledge of Solid Materials Traditional Areas: Metals, Polymers, Ceramics, Composites New Areas: Biomaterials, Nanomaterials

Materials Scientists & Engineers Study the Relationship Between Structure, Properties, and Processing of Materials Structure Properties Processing Materials

crystal an object with a regularly repeating arrangement of its atoms unit cell the simplest and smallest arrangement of atoms that can be repeated to form a particular crystal slip plane a surface along which layers of atoms can slide Terms

amorphouscrystalline

Unit Cells Constructed simple cubic body-centered cubic – BCC face-centered cubic – FCC hexagonal close packed – HCP BCC, FCC, and HCP are the most common crystal structures in metals

Simple cubic Face centered cubic Body centered cubic Hexagonal closest packed

Most Common Metal Crystal Structures BCC Body Centered Cubic FCC Face Centered Cubic HCP Hexagonal Close Pack

tialchemistry/flash/sphere9.swf Simple cubic tialchemistry/flash/sphere10.swf FCC tialchemistry/flash/sphere8.swf BCC UNIT CELLS

Workability Which crystal structure is more workable? Many slip planes or few slip planes? Tightly packed or loosely packed? (more or less “gappiness”?)

Crystal Structure and Workability Type of crystal structure Closely packed? Many slip planes? Workability FCC BCC HCP

Type of crystal structure Closely packed? Many slip planes? Workability FCCYesYesHighest BCC HCP

Type of crystal structure Closely packed? Many slip planes? Workability FCCYesYesHighest BCCNoYes HCP

Type of crystal structure Closely packed? Many slip planes? Workability FCCYesYesHighest BCCNoYes HCPYesNo

Type of crystal structure Closely packed? Many slip planes? Workability FCCYesYesHighest BCCNoYesMedium HCPYesNoLowest

BCCFCCHCPOther ChromiumAluminumCobaltManganese Iron (<912°C) CalciumMagnesiumTin MolybdenumCopperTitanium SodiumGoldZinc Tungsten Iron (>912°C) Lead Nickel Platinum Silver Crystal structures and metals

Mechanical Properties Examples workability malleability – can be flattened ductility – can be drawn into wire (stretched), bent, or extruded

Metal Property Changes Make it from different “stuff” Material Selection Disrupt the crystal structure Work Hardening, Cold Work Add different stuff to it Alloying Cool at different rates quench, anneal, temper

Dislocation (Line Defects ) regions in crystals where atoms are not perfectly aligned – an extra partial plane can move a small number make a metal more workable a large number make a metal harder to work dislocations can get “jammed” or “pinned” makes the metal harder = work- hardening

Alloys Mixture of metals or Metals and other elements

Treatment  ControlAnnealQuenchTemper Meaning of process XXXX Bobby pin High Carbon content Paper clip Low Carbon content HEAT TREATMENT OF STEEL

response to force or stress workability (malleability and ductility) Brittleness breaks instead of deforming Hardness resistance to denting or scratching elasticity and plasticity Toughness resistance to fracture ability to absorb energy strength resistance to distortion by stress Mechanical properties

WORK HARDENING- to strengthen a material by reshaping it while the part is cold. Heat Treating FORGING- shape or form metal by beating or hammering it ANNEALING - heat to red hot, air cool - metal is heated and cooled so that crystal can reform. - softens metal by relieving stress QUENCHING/ HARDENING - Steel - heat to red hot, quench in cool water - rapid cooling of metal (in water or oil) locks atoms into place in an unstable crystal structure - strengthens metal but brittle TEMPERING - Steel - heat to red hot, quench, re-heat to blue, air cool - heating material so atoms re-orient themselves - removes brittleness but keeps strength

Actual Applied Nitinol

Materials selection

Iron allotropes--- thermally manipulated Allotropes Different crystal structures of the same substance 44c6-83ca-d3bac9bc8f6d/diamonds-pencils- buckyballs-look-buckminsterfullerene Carbon allotropes strongest-material-graphene- pioneers.cnn/video/playlists/pioneers-orig/

ALLOTROPES OF CARBON

amorphouscrystalline

Borax = sodium borate decahydrate Heat the crystal and the water is driven out and then the crystal begins to lose its shape

Smarter every day PRdrop

CERAMICS Inorganic material with non-metallic properties made from raw materials mined from earth or chemically synthesized Metals or semi-metals (metalloids) strongly bonded to non-metals

Elements Used  All metals  Most semimetals – especially silicon  Some nonmetals  Mostly oxygen, and nitrogen  Also sulfur and phosphorus

History of Ceramics  Some claim ceramics were used in Japan 13,000 years ago  Evidence shows wide usage 6500 BC.  Glazed pottery in Egypt 4000 BC.  Glass beads in Egypt 2500 BC.  Fiber Optic 1960  Photovoltaic Cell 1965  Superconductor 1987

  How optical fiber is made corning

Superconductors

MRI (Magnetic Resonance Imaging) machines use superconductors to deliver a strong enough magnetic field so that hydrogen atoms in the body's fat and water molecules will pick up energy from the field which can then be detected by special instruments. SQUIDS (Superconducting QUantum Interference Device) can be used like an MRI, but without the need for a strong magnetic field. They can detect magnetic fields of infinitely small magnitudes. They can also be used for extremely precise motion detection.

  How superconducting levitation works Maglev trains Mobius strip

Polymers  Poly – many  Mer - parts  Long (gargantuan) chain molecules made of many smaller repeating units…perhaps as many as 100,000 repeats, often times tens of thousands polymers are

Premolds turning-markers-into-fuel/

Polymers  Thermoplastic  Melts with heat  Thermoset  Sets with chemical reaction  Elastomer  Is elastic