MATL 240 FINAL EXAM
Four Main Types of Engineering Materials - ANS-Metals, polymers, ceramics,
composites
2 Main Areas of Material Science - ANS-extractive material science and physical
material science
Extractive Material Science - ANS-Deals with removing raw material from the earth and
processing it into an engineering material
Physical Material Science - ANS-Deals with how the properities of materials are altered
by processing
3 Main Types of Material Properties - ANS-Physical, mechanical, chemical
Physical Properites - ANS-these are inherent to the material-Density, thermal
expansion, thermal conductivity, electrical conductivity
Mechanical Properties - ANS-how the material reacts or responds to an external
force-hardness, strength, ductility, toughness, impact strength, fatigue strength
Chemical Properties - ANS-how the material reacts with its environment-corrosion
resistance
Element - ANS-pure sucstance that can not be broken down into a simpler
substance-approximately two thirds of all elements are metallic
Atoms - ANS-smallest part of an element that retains the properties of the element
Atoms are made up of - ANS-protons, neutrons, electrons
Protons - ANS-in the nucleus, positive charge, approximately 1 AMU
Electrons - ANS-orbits the nucleus, negative charge, approximately 1/1837 AMU
Neutrons - ANS-in the nucleus, no charge, approximately 1 AMU
, Atomic Bonding - ANS-occurs because the atoms are trying to get to their lowest energy
state-this is when they have full outer electron shells (valence shells)
Main Types of Atomic Bonding - ANS-Covalent, Ionic, Vander Walls, Metallic
Covalent - ANS-one atom shares its valence electrons with another atom so each have
full valence electron shells
Ionic - ANS-one atom gives its valence electrons to another atom so each have full
valence electron shells-materials with ionic and covalent bonds are typically poor
electrical conductors because the electrons are held in fixed positions
Vander Walls - ANS-weak electrostatic bonds-important for thermoplastics
Metallic - ANS-"sea of electrons"-electrons move from atom to atom so each feels it has
a full valence shell-this makes metals good electrical conductors
States of Matter - ANS-Gas, liquid, solid
Gas - ANS-atoms do not have short range or long range order, shape and volume are
not fixed
Liquid - ANS-atoms have some short range order, volume is fixed, shape assumes that
of the container
Solid - ANS-atoms have long range order, shape and volume are both fixed
Solidification of Metals: 3 Stage Process - ANS-Step 1: Nucleation-two atoms that are
close together form a chemical bond
Step 2: Growth-additional atoms bond to the nuclei formed in stage one
Step 3: Formation of the Grain Boundaries-this occurs when grains of different
orientation intersect
Grain - ANS-area in a metal where the atoms have the same orientation
Smaller Grain= - ANS-stronger and less ductile-rapid solidification gives smaller grains
Crystalline - ANS-material where the atoms are in a 3D pattern-most metals are
crystalline
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