Material Science
The equation used to determine the approximate amount of critical stress to propagate a crack is known as the Griffith equation. The Griffith equation is given by σcritical ≈ _______________.
((2Eγ)/(πa))1/2
The Larson-Miller parameter is used to consolidate the stress-temperature-rupture time relationship into a single curve. The equation of the Larson-Miller parameter is L.M. = ____________.
(T/1000)(A + B ln t)
What is the electron structure for silicon?
1s2,2s2,2p6,3s2,3p2
What is the maximum number of electrons with opposing electronic spins allowed per orbital
2
The approximate value of the actual stress at the tip of a crack can be determined from the applied stress with the equation σactual = _______________.
2σ(a/r)(1/2)
Avogadros number is equal to___________
6.022*10^23
_______ are generally inorganic nonmetal materials that do not conduct heat well and must be heated to very high temperatures before melting. They are very strong and hard but also very brittle
Ceramics
The Arrhenius equation is a way to relate temperature or thermal energy to the rate of atom or ion movement. The Arrhenius equation is Rate=_____________________
Coexp(-Q/(RT)
If we load and unload low weight materials thousands of times, small _____________ will most likely begin to develop
Cracks
The lattice and bases concept and the unit cell concept both rely on the principles of _______________
Crystallography
The diffusion coefficient D is related to temperature by: D=
D0 exp (-Q/(RT)) \
Which of the following is not a crystal system for Bravais lattices
Decagonal
Pure carbon exists as several allotropes. The term allotrope refers to ____________________
Different arrangement of carbon atoms
A(n) ___________ dislocation is illustrated by slicing partway through a perfect crystal,spreading the crystal apart and partly filling the cut with an extra half plane of atoms
Edge
Metals which have been subject to significant corrosion will eventually _________ when a load is applied
Fail
An engineer is designing a plane. There is a choice of aluminum or a composite material. The composite weighs half that of aluminum. Choosing the composite will not affect fuel costs.
False
As we move down column 1A of the Periodic Table, chemical reactivity decreases
False
At low temperatures, it will usually only take a large number of atoms a short time to diffuse to produce a uniform structure
False
Cold working is never an inexpensive means of production.
False
Heating water to the boiling point breaks the van der Waals bonds and changes water to steam, but breaking covalent bonds requires much lower temperatures
False
It is impossible to increase the surface hardness of a material
False
It is not possible to determine differences in behavior of metals having different crystal structures by examining the force required to initiate the slip process
False
Magnetoelectrics are materials that develop spontaneous and reversible dielectric polarization
False
Most metals, semiconductors and ceramics have a crystalline structure in which the atoms or ions display short range order
False
Only one test currently exists for determining hardness.
False
Stress amplitude is defined as the average between the maximum and minimum stresses.
False
The presence of dislocations decreases the total internal energy of the structure
False
The process of progressively breaking and reforming bonds requires far more energy than the energy that would be requires to instantaneously break all of the binds across a slip plane
False
The ratio of sizes between the ionic radii of anions and cations in a cell has no influence on the manner of packing for that cell
False
The stresses that cause fatigue failure are often above the yield strength of the material.
False
The thermodynamic tendency of polycrystalline materials is to transform into materials that have a smaller average grain size
False
The valence of an atom is the number of electrons in an atom that do not participate in bonding in chemical reactions
False
There is no maximum amount of cold work or deformation that can be performed on a metallic material before it becomes too brittle and breaks.
False
When a metallic-glass compression sample is deformed at a constant displacement rate, the load will remain constant.
False
In processes such as wire extrusion a(n) __________ texture is produced. This term refers to the grains in the metallic material, which become elongated in a direction parallel to the axis of the extruded product.
Fiber
_____________stress is the stress needed to initiate plastic flow in a previously deformed material.
Flow
Elements such as silicon, germanium, a-Sn, and carbon are bonded by _____________ bonds and produce a tetrahedron
Four covalent
A _____________________ is a vacancy- interstitial pair formed when an ion jumps from a normal lattice point to an interstitial site and leaves behind a vacancy
Frenkel defect
Fick's first law is given by the equation _______________
J = -D((dc)/(dx))
_____________ have good electrical and thermal conductivities, relatively high strength , high stiffness, ductility or formability and shock resistance. These materials are particularly useful for structural or load-bearing applications
Metals and Alloys
If the relationship between the applied shear stress and the shear strain rate is linear, we refer to that material as__________. If the relationship between shear stress and shear strain rate is nonlinear, these materials are __________.
Newtonian, non-Newtonian
____________ occurs when a stress is removed and the material does not go back to its original shape.
Plastic deformation
_________ are typically organic materials. They are usually good electrical and thermal insulators and generally have very good strength to weight ratios. They are generally not suitable for high temperature applications
Polymers
Metallic, covalent, and ionic bonds are known as _____________
Primary bonds
The three stage of annealing are:
Recovery, Recrystallization, Grain Growth
The equation for determining engineering stress is __________ and the equation for engineering strain is __________.
S=F/Ao, e=Δl/lo
In materials containing vacancies, atoms move from one lattice position to another. This process is known as _____________.
Self_diffusion
Which of the following is not an example of van der Waals interactions?
Stambuli
A way to form compressive stresses on the surface of glass is to heat the glass just below a specific temperature then let the glass cool more quickly on the surface than the center. This process is known as ____________.
Tempering
What is the atomic number of an atom?
The number of protons per atom
What is the relationship between a miller index value and its negative value
The vectors represent the same line, but point in opposite directions
Fick's second law allows us to determine the concentration of one diffusing species as a function of ______________ and __________
Time, location
A number of factors are taken into account when an engineer chooses a material to use is a project. These factors can include but are not limited to: costs, weight, conductivity
True
Activation energies are lower for interstitial diffusion than for vacancy diffusion
True
Artificial organs, bone replacement parts, cardiovascular stents, orthodontic braces and other components are made using different plastics, titanium alloys, and nonmagnetic stainless steels
True
Ceramics normally have poor toughness, even if they display high strength, because they have virtually no ductility. These materials show both poor tensile toughness and poor impact toughness.
True
Changes in temperature dramatically alter the properties of materials
True
Covalently bonded materials frequently have complex structures in order to satisfy the directional restraints imposed by the bonding
True
For load-bearing applications, engineered materials are selected by matching their mechanical properties to the component's design specifications and service conditions.
True
Grain growth will occur in most materials if they are subjected to a high enough temperature.
True
Metallic materials that have undergone work hardening possess increased strength but reduced ductility
True
Nanoindentation techniques are important for deforming free-standing micro and nanoscale structures.
True
No strengthening occurs during deformation by hot working; consequently, the amount of plastic deformation is almost unlimited.
True
Repeated temperature change encourages failure by thermal fatigue.
True
The Aufbau Principle is a device that helps determine deviations from expected ordering of the energy levels
True
The critical stress needed to initiate plastic deformation is the elastic limit of the material.
True
The direction of a Miller index and its multiple are the same
True
The mechanism of increasing the strength of a material by deformation is know as strain hardening
True
The term KIc is known as the plane strain fracture toughness and does not depend upon the thickness of the sample.
True
The two most common measures of ductility are percent elongation and percent reduction.
True
Density is the ratio of ___________
Weight/Volume
In cold working, the amount of deformation is measured by defining the percent cold work. The equation for percent cold work is _____________.
[(Ao-Aƒ)/(Ao)] x 100
The ______________ is the number of atoms touching a particular atom, or the number of nearest neighbors for that particular atom.
coordination number
Bonds that are formed by the sharing of valence electrons among two or more atoms are
covalent bonds
A material is ____________ if its properties depend on the crystallographic direction along which the property is measured. If the properties are identical in all directions, the material is _____________
crystallographically anisotropic, crystallographically isotropic
In metals, the yield strength decreases rapidly at higher temperatures due to a decreased _____________ density and an increase in ______________.
dislocation, grain size
Crystal structures with ions must have ________
electrical neutrality
The Weibull modulus is between 5 and 10 for _______
engineered ceramics
The ___________ demonstrates how long a part may survive or the maximum allowable loads that can be applied without causing failure.
fatigue test
In Fick's first law the J is the _____________, D is the ____________________ and dc/dx is the ____________
flux, diffusivity coefficient, concentration gradient
Materials with high bonding energy also have _________________ strength and ___________ melting temperatures
high, high
BCC metals tend to have _______ and ________ compared to FCC metals
higher strengths, lower ductilities
The ability of a material to withstand an impact blow is often referred to as the __________ of the material.
impact toughness
The driving force for recrystallization is the difference between the ____________ of a cold-worked material and that of a recrystallized material.
internal energy
A(n) ______________________ is formed when an extra atom or ion is inserted into the crystal structure at a normally unoccupied position
interstitial defect
Compounds can be formed from two or more metals. When the difference in electronegativity between the metals is very large, these compounds may be bonded by a mixture of metallic and ______________ bonds
ionic
A lattice is a collection of points named _____________, which are arranged in a periodic pattern so that the surroundings of each point in the lattice are identical
lattice points
As local stress increases, ___________ grow and coalesce into larger cavities.
microvoids
Material dislocations must be introduced into the crystal structure of a material in order to induce a nonuniform shape change. Such dislocations are called geometrically ___________________.
necessary dislocations
In many ductile materials, deformation does not remain uniform. At some point, one region deforms more than others and a large local decrease in the cross-sectional area occurs. This phenomenon is known as ______________.
necking
_____________ refers to irreversible deformation that occurs when the force or stress that caused the deformation is removed
plastic deformation
Localized disruptions in otherwise perfect atomic or ionic arrangements in a crystal structure are called_____________________
point defects
In the solidification process, the production of metallic slabs or ingots is known as __________. The process of turning the metallic slabs or ingots into useful shapes is known as ___________.
primary processing, secondary processing
The process of forming new grains by heat-treating a cold-worked material is known as ______________.
recrystallization
In a creep test, the time required for failure to occur is the ______________.
rupture time
Select the option below that includes the names for all three cubic crystal Bravais lattices
simple cubic, face-centered cubic, body-centered cubic
___________ is a phenomenon in which materials react with corrosive chemicals in the environment. This leads to the formation of cracks and a lowering of strength.
stress corrosion
The Peierls-Nabarro stress is the stress required to move a dislocation from one equilibrium location to another
true
____________ is known as the Hall-Petch Equation. This equation relates a material's grain size to its yield strength.
σy = σ0 + Kd^-1/2
