Introduction to Material Science
and Engineering
Introduction
What is materials engineering?
the understanding and modification of the structure
and properties of materials to improve the
performance and processing of the material
What is a material scientist/engineer?
A person who uses his/her combined knowledge of
physics, chemistry and metallurgy to exploit
property-structure combinations for practical use.
What are materials?
What do we mean when we say “materials”?
1. Metals
2.
- aluminum
- copper
- steel (iron alloy)
- nickel
- titanium
Ceramics
3. Polymers
4.
- clay
- polyvinyl chloride (PVC)
- silica glass
- Teflon
- alumina
- various plastics
- quartz
- glue (adhesives)
- Kevlar
Composites
- wood
- carbon fiber resins
- concrete
semiconductors (computer chips, etc.) = ceramics, composites
nanomaterials = ceramics, metals, polymers, composites
Classes of Materials
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metals
polymers
ceramics
composites
Stone Age – up to around 3000 B.C.
• tools and weapons of stone, copper (some
silver and gold) used mostly for ornamental
purposes, but too soft for much else
Bronze Age– 3000 BC to 1000 BC
• tools and weapons made from a combination
of copper and tin
Iron Age – 1000 BC to present
• weaker than bronze, but didn’t require being
alloyed with another metal, also could be
sharpened
• Later combined with carbon to create steel, a
much stronger metal
Definitions
• Elastic deformation – Reversible alteration of the form or
dimensions of a solid body under stress.
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• Plastic deformation - Irreversible alteration of the form or
dimension of a solid body under stress.
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• Brittle – Ability of a material to break, snap, crack or fail
easily when subjected to external loads.
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• Ductile – Ability of a material to undergo permanent
deformation through cross-section reductions and
elongation without fracture.
Metals
• Metal alloys are mixtures of two or more metal and
nonmetal elements (for example, aluminum and copper,
Cu-Ni alloy, steel)
• Properties:
– Electrically conductive (free electrons)
– Thermally conductive
– High strength – large capacity to carry load over crosssection area (stress)
– Ductile – endure large amounts of deformation before
breaking.
– Magnetic
– Medium melting point
Metal Applications
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Electrical wire: aluminum, copper, silver
Heat transfer fins: aluminum, silver
Plumbing: copper
Construction beams (bridges, sky scrapers, rebar, etc.):
steel
• Cars: steel
• Consumer goods:
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soup cans
appliances (stainless steel sheet metal)
utensils
tools
Many, many, many more…
Polymers
• Polymers consist of various hydro-carbon (organic
elements) with select additives to bring out
specific properties
• Properties:
– ductile: can be stretched up to 1000% of original
length
– lightweight: Low densities
– medium strength: Depending on additives
– chemical stability: inert to corrosive environments
– low melting point
Polymer Applications
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Car tires: vulcanized polymer (added sulfur)
Ziploc bags
Food storage containers
Plumbing: polyvinyl chloride (PVC)
Kevlar
Aerospace and energy applications: Teflon
Consumer goods:
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calculator casings
TV consuls
shoe soles
cell phone casings
Elmer’s Glue (adhesives)
contact lenses
Many, many. many more…
Ceramics
• Consist of metal and non metal elements
• Typically a mixture of elements in the form of a
chemical compound , for example Al2O3 or glass
• Properties:
– wear resistant (hard)
– chemical stability: corrosion resistant
– high temperature strength: strength retention at very
high temperatures
– high melting points
– good insulators (dielectrics)
Ceramic Applications
• Window glassAerospace, energy and automotive
industry
– heat shield tiles
– engine components
– reactor vessel and furnace linings
• Consumer products:
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pottery
dishes (fine china, plates, bowls)
glassware (cups, mugs, etc.)
eye glass lenses
Composites
• A mixture of two different materials to create a new material
with combined properties
• Types of composites:
– Particulate reinforced
– Whisker/rod reinforced
– Fiber reinforced
– Laminated composites - layered structures (surf boards,
skate boards)
• Properties: Depends on composites
– High melting points with improved high temperature
strength: ceramic-ceramic
– High strength and ductile with improved wear resistance:
metal-ceramic
– High strength and ductile: polymer-polymer
Composites: Applications
• Wood: naturally occurring biological material
consists of very strong fibers imbedded in a soft
matrix
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Plywood: laminated wood for buildings
Concrete: basements, bridges, sidewalks
Fiberglass: boats
Carbon fiber resins: bicycle frames
Additional Properties of Materials
• Electrical Properties
– Conductivity – how well electricity flows through a
material
– Resistivity – how well a material resists the flow of
electricity
• Magnetic Properties
– high magnetic permeability = magnetic flow
Additional Properties of Materials
• Chemical Properties
– Flammability – how easy it is to ignite
– Corrosion – reaction between material and
environment that leads to deterioration
• Thermal Properties
– Thermal Conductivity – how well heat is
transferred
– Thermal Resistance – how well heat is resisted
• Expressed with an “R-Value”
• High R-value = less heat flow
Additional Properties of Materials
• Optical Properties
– Reflection/Absorption – if something is “blue” it
absorbs all other light but blue, which is reflected
back
• Acoustic Properties
– Absorption – more porous materials absorb more
sound
– Reflection
• Smoother materials reflect sound in one direction
• Rough materials reflect sound in multiple directions
Nanotechnology
• Nanotechnology – the design of new materials
and devices at the scale of a single nanometer
• Nanoparticles – between 1nm and 100nm, at the
nanoscale material properties can be different
than in larger scales (i.e. gold can melt at room
temperature)
• Nanowires – small strands designed to transmit
light or electricity
• Nanotubes – lightweight and stronger than steel
• Buckyball – most round molecule known to man,
ideal for “carrying” other atoms or particles