MSE 200/201 Exam 1 Review

What is an element with more than one atomic mass called?

An isotope

Between two materials with different net energy, which has a higher melting temperature?

The material with the higher net energy

family of direction

< >

What characterizes crystalline materials?

Long periodic order of atoms

How does diffusion change with temperature?

It increases exponentially

Flux (J) is proportional to what?

Concentration gradient

In non-steady state diffusion, the concentration of diffusing species is a function of what?

Both time and position

What are materials comprised of many small crystals or grains with different crystallographic orientations called?

Polycrystalline materials

What are materials with atoms in a repeating or periodic array over their entire extent called?

Single crystalline materials

What are materials with properties that do not vary with direction called?

Isotropic

What are materials with properties that vary with direction called?

Anisotropic

What characterizes noncrystalline materials?

No periodic order in terms of packing of atoms

What are the regions between grains with crystallographic misalignment called?

Grain boundaries

What is the orientation of the Burger's vector (b) of an edge dislocation relative to the dislocation line?

Perpendicular

When is the equilibrium separation between two atoms achieved?

When net force is zero and net energy is minimized

How does the number of vacancies change with increasing temperature?

It increases exponentially

What is the packing sequence for FCC?

ABCABC....

What is the packing sequence for HCP?

ABABAB.....

What is the relationship between 'a' and 'r' for a BCC lattice?

a = 4R/√3

What is the relationship between 'a' and 'r' for an FCC lattice?

a = 2√2R

What are two common diffusion mechanisms?

Vacancy and interstitial diffusion

What is the term for two or more distinct crystal structures for the same material?

Allotropy

Vacancies, self-interstitials, interstitial impurities, and substitutional impurities are considered what type of defects?

Point defects

What are the 4 Hume-Rothery solubility rules?

(1) max 15% difference in radius, (2) same crystal structure, (3) similar electronegativity, (4) similar valence

What is the closed-packed plane for the BCC crystal structure?

(110)

What is the closed-packed plane for the FCC crystal structure?

(111)

What is the electron configuration for Fluorine?

1s2 2s2 2p5

What is the total number of valence electrons for Mg?

2

What type of bonding is directional?

Covalent bonding

What type of bonding is used for metallic elements?

Metallic bonding

What type of non-directional bonding is used for ceramics?

Ionic bonding

Which atoms are most likely to be an interstitial impurity?

Carbon, oxygen, nitrogen, boron, and hydrogen

Which crystal structure has the highest APF (atomic packing factor)?

FCC

Which occurs faster: interstitial diffusion or vacancy diffusion?

Interstitial diffusion

Which type of imperfection is a line defect?

Dislocation

edge dislocation

burger vector is perpendicular

screw dislocation

burger vector is parallel

Nv

number of vacancies

N

total number of lattice sites

N equation

n / VC

n

atoms per unit cell

Vc

volume of unit cell

A

molar mass

crystal structure best for interstitial impurity

BCC

ionic bond

metal and non metal

positive and negative charges

metallic bond

sea of charges

van der waals

weak, secondary bonding

vectors

[ ]

CP planes BCC

none

closest is {110}

CP direction BCC

<111>

CP plane FCC

{111}

CP direction FCC

<110>

if z needs to be found

(z want - z little erf(z))/(big erfz - little erfz) = erfz values

planes

( )

family of planes

{ }