Introduction to Material Sci-Eng

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Fundamentals of materialsScience and Engineering

Credits: 3+1ECTS : 6

1Prof. Dr. Hatem AKBULUT


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Introduction to MaterialsScience and Engineering

1.1 What is Materials Science andEngineering?

1.2 Classification of Materials

1.3 Functional Classification ofMaterials

1.4 Classification of Materials Basedon Structure

1.5 Environmental and Other Effects

1.6 Materials Design and Selection

Prof. Dr. Hatem AKBULUT


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Section 1.1What is Materials Science and

Engineering?

Materials Science and Engineering

Composition means the chemical make-up of amaterial.

Structuremeans a description of the arrangementsof atoms or ions in a material.

Synthesisis the process by which materials aremade from naturally occurring or other chemicals.

Processingmeans different ways for shapingmaterials into useful components or changing theirproperties.



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Materials Science

Mater. Sci. investigates relationshipsbetween structure and properties

Mater Sci. teaches basic concepts andprinciples for all materials with regard to

Physics, Chemistry and Mathematics.



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Structure

Electronic StructureElectronic structure specifiesinteractions between atoms

(interatomic bond formation)

Atomic Structure

Atomic arrangements inmaterials



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Microscopic Structure

The arrangement of smallgrains that can only be

determined withmicroscopes

Macroscopic StructureStructural elements thatcan be seen with naked eye

Structure



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Angstrom = 1 = 1/10,000,000,000 meter = 10-10

mNanometer = 10 nm = 1/1,000,000,000 meter = 10-9m

Micrometer = 1m = 1/1,000,000 meter = 10-6mMillimeter = 1mm = 1/1,000 meter = 10-3m

Interatomic distance ~ a couple Humans hair ~ 50 m



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2003 Brooks/Cole Publishing / Thomson Learning



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2003Brooks/ColePublishing

/ThomsonLearning

Figure 1.1 Application of the tetrahedron of materials scienceand engineering to ceramic superconductors. Note that themicrostructure-synthesis and processing-composition are allinterconnected and affect the performance-to-cost ratio



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Figure 1.2 Application of the tetrahedron of materials scienceand engineering to sheet steels for automotive chassis. Notethat the microstructure-synthesis and processing-compositionare all interconnected and affect the performance-to-cost ratio

2003Brooks/ColePublishing/ThomsonLearning



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Figure 1.3 Application of the tetrahedron of materialsscience and engineering to semiconducting polymers formicroelectronics



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Section 1.2Classification of Materials

Metals and AlloysCeramics, Glasses,and Glass-ceramicsPolymers (plastics), Thermoplastics and Thermosets

SemiconductorsComposite Materials



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Table 1.1 Representative examples,applications, and properties for each

category of materials

Example of Applications Properties

Metals and AlloysGray cast iron Automobile engine blocks Castable, machinable,

vibration dampingCeramics andGlassesSiO2-Na2O-CaO Window glass Optically transparent,

thermally insulatingPolymersPolyethylene Food packaging Easily formed into thin,

flexible, airtight film



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Example of Applications Properties

SemiconductorsSilicon Transistors and integrated Unique electrical

circuits behavior

Composites Carbide cutting tools for High hardness, yetTungsten carbide machining good shock resistance-cobalt (WC-Co)

Table 1.1 Continued



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Figure 1.4 Representative strengths of various categories ofmaterials



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17Prof. Dr. HatemAKBULUT


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Figure 1.5 A section through ajet engine. The forwardcompression section operates at

low to medium temperatures,and titanium parts are oftenused. The rear combustionsection operates at hightemperatures and nickel-basedsuperalloys are required. The

outside shell experiences lowtemperatures, and aluminumand composites are satisfactory.(Courtesy of GE AircraftEngines.)

Figure 1.6 A variety of complexceramic components, includingimpellers and blades, which allow

turbine engines to operate moreefficiently at highertemperatures. (Courtesy ofCertech, Inc.)



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2003

Brooks/ColePublishing/ThomsonLearning

Figure 1.7 Polymerization occurs when small molecules,

represented by the circles, combine to produce larger molecules,or polymers. The polymer molecules can have a structure thatconsists of many chains that are entangled but not connected(thermoplastics) or can form three-dimensional networks inwhich chains are cross-linked (thermosets)



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Figure 1.8 Polymersare used in a variety

of electronicdevices, includingthese computer dipswitches, wheremoisture resistanceand low

conductivity arerequired. (Courtesyof CTS Corporation.)

Figure 1.9Integrated circuits

for computers andother electronicdevices rely on theunique electricalbehavior ofsemiconducting

materials.(Courtesy of RogersCorporation.)

Figure 1.10 The X-wing for advanced

helicopters relies ona material composedof a carbon-fiber-reinforced polymer.(Courtesy of SikorskyAircraft Division

United TechnologiesCorporation.)



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Section 1.3Functional Classification of

MaterialsAerospaceBiomedicalElectronic Materials

Energy Technology and Environmental TechnologyMagnetic MaterialsPhotonic or Optical MaterialsSmart MaterialsStructural Materials



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Figure 1.11Functionalclassification ofmaterials.Notice thatmetals, plastics,and ceramicsoccur indifferentcategories. Alimited number

of examples ineach category isprovided



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Section 1.4Classification of Materials-Based on Structure

Crystalline materialis a material comprised of one ormany crystals. In each crystal, atoms or ions show along-range periodic arrangement.

Single crystalis a crystalline material that is madeof only one crystal (there are no grain boundaries).Grains are the crystals in a polycrystalline material.Polycrystallinematerialis a material comprised ofmany crystals (as opposed to a single-crystal materialthat has only one crystal).Grain boundaries are regions between grains of apolycrystalline material.



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Section 1.5Environmental and Other Effects

Effects of following factors must be accounted for indesign to ensure that components do not failunexpectedly:

TemperatureCorrosionFatigueStrain Rate



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2003Brooks/ColePub

lishing/ThomsonLearning

Figure 1.12Increasingtemperature normallyreduces the strengthof a material.Polymers are suitable

only at lowtemperatures. Somecomposites, specialalloys, and ceramics,have excellentproperties at high

temperatures



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2003Brooks/ColePublish

ing/ThomsonLearning

Figure 1.13 Skin operating temperatures for aircraft haveincreased with the development of improved materials.(After M. Steinberg, Scientific American, October, 1986.)



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Figure 1-14 Schematic of a X-33 plane prototype. Notice the

use of different materials for different parts. This type ofvehicle will test several components for the Venturestar(From A Simpler Ride into Space, by T.K. Mattingly,October, 1997, Scientific American, p. 125. Copyright 1997 Slim Films.)



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Section 1.6Materials Design and Selection

Densityis mass per unit volume of a material,usually expressed in units of g/cm3or lb/in.3

Strength-to-weight ratiois the strength of a materialdivided by its density; materials with a high strength-to-weight ratio are strong but lightweight.



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