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31 Cards in this Set

  • Front
  • Back
Be able to describe the concept of phases?
Phases (or state)diagrams represent the different phases that a substance can go through.
Example H20 Solid phase is ice
Liquid phase is water, the gaseous phase of H2O is steam.
What are the two forms that solids come in?
Solids occur 2 forms:
Crystalline solids and
Amorphous solids
What are crystalline solids?
They possess an ordered three-dimensional geometric arrangment that repeats itself.
The majority of engineering and structural materials are crystaline ex. metals
What is crystallography?
Study of crystalline structures
What are unit cells?
They are used to describe the basic building blocks of basic geometric arrangement of atoms in a crystal.
What do the points on a unit cell represent?
The points on the unit cell represents atoms, ions or molecules of differing sizes.
What do the lines on a unit cell represent?
The lines (labeled a, b & c) on the unit cell represent the lattice parameters in the x,y, & z directions. They are also known as intercepts.
A bunch of unit cells put together make up what?
The angles represent the angle measured in degrees between different planes. ?
What are the 7 crystal structures?
What are the 14 space lattices?
Cubric-simple,body centered, face centered
Tetragonal-simple, body centered,
Orthohombic-simple, base centered, body centered, face centered
Monoclinic-simple, body centered
Know the difference cubic space lattices?
see previous question
What is the coordination number?
Coordination number (CN) is the number of neighboring atoms that each atom has immediately surrounding it.
The coordination number depends on what two factors?
The type of bonding and the realtive size of the atoms or ions involved.
What is the coordination number for a simple cubic structure?
Simple cubic CN=6

Body centered cubic CN=8

Face centered cubic CN=12
What is the difference between an allotrophic material and a polymorphic material?
A allotrophic material can, after changing from one crystal structure to another reverse the phenomenon and return to its previous structure A polymorhic material CANNOT,
What are crystal imperfections?
What are their function?
2 part question
Represent defects in the perfect atomic arrangement and should not suggest that the material itself is defective.
Defects are often intentionally added to produce a desired set of mechanical or physical properties.
Crystal imperfections fall into what two categories?
Crystal impurities and crystal defects.
What are crystal impurities?
Involve impure atoms
Crystal impurities occur when a small percentage of one material is added to another material.
What is an example of a crystal impurity?
An example of an impurity refers to the small percentage of copper in sterling silver that distinguishes sterling from pure silver. An example whould be alloys
What is the difference between a mixture and a solid solution?
In a mixture the two crystal structures remain distinct.

In a solid solution the two crystal structures of copper and zinc are said to diffuse to create one crystal structure.
What is an example of a mixture and an example of a solid solution?
Steel is a mixture of iron with a bcc structure and cementite with a fcc structure.
Brass is a solid solution (copper and zinc) because its sigle phase structure is all fcc.
What are the different crystal defects?
Point defects
Line defects
Area defects
Vacancy is an example of what?
Point Defect

(absence of an atom at a lattice site in an otherwise regular crystal)
What are line defects?
aka dislocations.
A dislocation is a linear array of atoms along which there is some imperfection in the bonding of the atoms.
What are the two dislocations?
Edge dislocation and Screw dislocation
What is the difference between an edge dislocation and a screw dislocation?
Edge-when an extra row or plane of atoms is either added or eliminated
Screw-when a torsional force is applied to the lattice.
What is the slip plane?
Plane on which the displacement of the atom occurs.
What are area defects?
Area defects are surface defects
What are amorphous solids?
They do not have anyt repetitious patterns of atoms

Polymers are examples of amorphous solids and they have four basic structures
What are the four basic amorphous structures?
Linear polymers, branched polymers,
cross-linked polymers,
ladder polymers.
What type of amorphous structure does PVC and glass have?
Linear Polymers (PVC)

Cross-Linked Polymers (Glass)