mte 271 final
cast irons are a series of high carbon ferrous alloys. These alloys are used for a variety of purposes including as frying pans and engine blocks. what is the typical carbon concentration range for cast irons?
3-4.5
If a specimen of this steel is solutionized (aka, annealed to equilibrium) at 800°C and then rapidly quenched to room temperature, what constituents will make up the microstructure?
martensite
Li=
maximum length of stretching
peritectoid
multiple solid phases to less solid phases S1+S2->S3
Please select the metals or alloys that may be used to galvanically protect nickel that is in the active state
must be elements that lie below on the table... tin, lead, 316 and 304 stainless steels, cast iron, iron, steel, aluminum alloys, cadmium, commercially pure aluminum, zinc, magnesium, and magnesium alloys
A semiconductor has an energy band gap that is relatively
narrow
Lo=
original length before stretching
In corrosion, the reduction reaction occurs at the ___ and the oxidation reaction occurs at the ___
oxidation-anode reduction-cathode
If a specimen of this steel is solutionized (aka, annealed to equilibrium) at 800°C, rapidly cooled to 550°C and is held at 550°C for 10 seconds, and is then quenched to room temperature, what constituents will make up the microstructure?
pearlite
Kic
plane strain fracture toughness
The term ___________ is used for compounds with more that one crystal structure.
polymorphic
once the system is at a state of equilibrium, a shift of equilibrium may result by alteration of which of the following?
pressure, composition, temperature
Pt=
radius of curvature of crack
covalent bonds are formed by
sharing of valence electrons with opposite spins
eutectic phase diagram-
sliver on left, rectangle on bottom, three triangles on top L->S1+S2 one liquid and two solids
eutectoid-
solid phase into two different solids phase S1->S2+S3
ε
strain
σ
stress
The solvent is an element or compound that is present in ...
the greatest amount
coordination numbers (CN) refer to:
the number of nearest neighbors surrounding a a particular atom or ion
The atomic number characterizes each element and is equivalent to:
the number of protons inside the nucleus of an atom
the motif (aka basis) refers to:
the objects that are placed on lattice points to build up a crystal structure
1 GPa=
10 ^9 Pa
Name the two general states that accompany a phase transformation
Growth, nucleation
Calculate the heat flux (in W/m^2) through a sheet of a metal 14 mm thick if the temperatures at the two faces are 350 and 140°C. Assume steady-state heat flow and that the thermal conductivity of this metal is 52.4 W/m-K.
heat flux can be calculated using the following equation: q = −k(ΔT/Δx) q = −(52.4 W/m-K) ((140°C - 350°C))/(14E-3 m)) = 7.86E5 W/m2
ionic crystals must exhibit _____
higher melting temperature large elastic modulus small coefficient of thermal expansion
a p-type semiconductor...
holes are the majority carriers doped with group 3 elements to add holes
consider a metal matrix composite consisting of an aluminum matrix reinforced with silicon carbide particles. In general, as the particle content is increased, how does the strength of this particle-reinforced metal-matrix composite change?
increases
2a=
length of internal crack
a=
length of the surface crack
Are energies for holes greater or less than the Fermi energy?
less than
a liquidus line separates which of the following phase fields?
liquid and liquid+alpha
The typical electrical conductivity value/range for Insulator materials are:
10^-20 to 10^-10 (Ω-m)-1
The typical electrical conductivity value/range for Semiconductor materials is:
10^-6 to 10^4 (Ω-m)^-1
1 MPa= ___ Pa
10^6 Pa
The typical electrical conductivity value/range for Metal materials is:
10^7 (Ω-m)-1
refractory ceramics are used to line vessels that hold molten metal or molten glass prior to casting. what are some desirable characteristics of refractory ceramics?
-ability to withstand high temps -ability to remain unreactive and inert -low thermal conductivity
aluminum alloys are commonly used in beverage cans and in aircraft. Which of the following are some desirable characteristics of aluminum?
-can be manufactured to have high strength -high corrosion resistance -high thermal conductivity -high specific strengths (low density)
Consider an ionic compound that is composed of cations with a radius of 0.137 nm and anions with a radius of 0.241 nm. Assume atomic weights of 22.7 g/mol and 91.4 g/mol for the cations and anions, respectively. (1 nm = 10-9 m = 10-7 cm) Calculate the lattice parameter for this ionic compound in units of cm.
-first, find the ratio of cations to anions to find the CN. then determine the crystal structure -use the formula for lattice parameter, but use r as (ranion + rcation)
Which of the following materials are considered to be composites?
-pearlitic steel -wood -bone -concrete -carbon fiber reinforced epoxy -ductile cast iron -fiberglass
Why do we add plasticizers to polymers?
-to improve flexibility -to improve toughness
CN for simple cubic
6
A Frenkel defect is composed of which of the following?
A cation interstitial and a cation vacancy
A Schottky defect is composed of which of the following?
A cation vacancy and an anion vacancy
peritectic-
A peritectic reaction is a reaction where a solid phase and liquid phase will together form a second solid phase at a particular temperature and composition - e.g. L+S1->S2
Hard magnetic materials display which of the following characteristics?
Arelatively large hysterisis loop Magnetization and demagnetization require relatively high applied fields
what differentiates atomic structures from crystal structures?
Atomic structure relates to the number of protons and neutrons in the nucleus of an atom, as well as the number and probability distributions of the constituent electrons. Crystal structure pertains to the arrangement of atoms in the crystalline solid material.
For nonmetallic materials, what is the name of the region that lies between the valence and conduction bands?
Energy band gap.
For a p-type semiconductor... Electron concentration ____ Hole concentration
For a p-type semiconductor, the concentration of electrons is much lower than the concentration of holes.
For an n-type semiconductor, where is the Fermi level located?
Just below the conduction band in the band gap.
If the original specimen length is 300 mm, calculate the maximum length to which the specimen may be stretched without causing plastic deformation?
Li = Lo(1+ε) = Lo(1+(σ /E))
Which of the following materials may form crystalline solids?
Metals Polymers Ceramics
1 MPa=
N/mm^2
Is impervious to light transmission.
Opaque
Consider an ionic compound that is composed of cations with a radius of 0.137 nm and anions with a radius of 0.241 nm. Assume atomic weights of 22.7 g/mol and 91.4 g/mol for the cations and anions, respectively. (1 nm = 10-9 m = 10-7 cm) Using the given information, determine the coordination number for this ionic compound.
R(cation)/R(anion) = ratio, use chart to locate the CN
How do thermal conductivities of single crystals and polycrystalline materials compare?
Single crystal conductivity is greater, because both phonons and free electrons are scattered at grain boundaries; thus, the efficiency of thermal transport is lower for the polycrystalline material
Transmits light diffusely
Translucent
Transmits light with relatively little absorption
Transparent
Increasing the number of grains or increasing the grain size of a metal material causes the strength of the metal to decrease.
True
Consider an ionic compound that is composed of cations with a radius of 0.137 nm and anions with a radius of 0.241 nm. Assume atomic weights of 22.7 g/mol and 91.4 g/mol for the cations and anions, respectively. (1 nm = 10-9 m = 10-7 cm) Calculate the theoretical density in units of g/cm3 for this ionic compound.
[4 atoms * ( sum of the densities)] / [(a^3)(avagadros number)]
isotherm
a line on a map connecting points having the same temperature at a given time or on average over a given period
For most technologically important metal alloys, the usual state or microstructure is:
a metastable one
lattice parameter for BCC
a= 4r/√3
lattice parameter for simple cubic
a=2r
lattice parameter for FCC
a=4r/√2
The term _________ refers to pure elements with more that one crystal structure.
allotropic
a solvus line separates which of the following phase fields?
alpha and alpha+beta
a solidus line separates which of the following phase fields?
alpha and liquid+alpha....... look on graph to see which is where S1 and S1+ L
A binary composition vs. temperature phase diagram for an isomorphous system will be composed of regions that contain which of the following phases and/or combinations of phases?
alpha, liquid+alpha, liquid
The oxidation of an atom is a process that involves
an atom gives up an electron
λ=
angle between slip direction and tensile stress direction cosλ= [u1u2+v1v2+w1w2]/sqrt[(u1^2+v1^2+w1^2)(u2^2+v2^2+w2^2)]
ϕ=
angle between the tensile stress direction and the plane NORMAL to the slip plane- (number are same but in brackets instead of parenthesis)
Metals located near the bottom of the galvanic series are
anodic reactive
If a specimen of this steel is solutionized (aka, annealed to equilibrium) at 800°C, rapidly cooled to 300°C and is held at 300°C for 1 day, what constituents will make up the microstructure?
bainite
isomorphous phase diagram-
basic diagram, one sliver of overlap
Metals located near the top of the galvanic series are
cathodic unreactive
Select what determines the characteristic color of a metal.
distribution of wavelengths of reflected light
what are the two fundamental types of dislocations?
edge, screw
E
elastic modulus
σ (electricity)
electrical conductivity 1/ρ
metallic bonds are formed by
electron cloud
an n-type semiconductor...
electrons are the majority carriers doped with group 5 elements to add electrons
The charge carriers in ionic ceramics can be...
electrons, holes, anions, cations (all of the above)
The ratio of sizes of the ionic radii of anions and cations in a cell has no influence on the manner of packing of that cell.
false
The following describes which type of magnetism: permanent and aligned magnetic moments that result from the incomplete cancellation of magnetic spin moments; these are present even in the absence of an external field?
ferrimagnetism
In which of the following phenomena do free electrons play a role: thermal conduction or thermal expansion?
thermal conduction
Polymeric materials are often referred to as plastics. We often classify plastics by the mechanism of polymerization. Which of the following mechanisms best describes plastics?
thermosetting and thermoplastic
small angle boundaries formed by edge dislocations are called
tilt boundaries
ionic bonds are formed by
transfer of electrons
when light interacts with matter it is said to be attenuated. Attenuation of light by matter can occur in which of the following ways?
transmitted absorbed reflected scattered
"Coring," which represents a form of non-equilibrium solidification, results in variations in the composition of a solidifying alloy. Coring occurs because of rapid solidification (i.e., the alloy solidifies faster than diffusion can occur to equilibrate composition). Is this true or false?
true
In precipitation hardening, the solution heat treatment consists of (1) heating the alloy to a temperature such that all solute atoms are dissolved to form a single-phase solid solution, and (2) quenching to produce a nonequilibrium supersaturated solid solution. The alloy is then aged at a lower temperature to form a uniform distribution of small precipitates. Is this true or false?
true
the surface energy of a single crystal depends on the crystallographic orientation with respect to the surface
true
small angle boundaries formed by screw dislocations are called
twist boundaries
tie line
type of isotherm connecting two phase lines on a diagram
the electrons that occupy the outermost filled shell are called ______ electrons
valence
lever rule
wa=cb-c0/cb-ca wb=c0-ca/cb-ca
critical resolved shear stress=
σ cosλ cosϕ