MSE 230 - Exam 1
Which of the following indicates a single plane within a unit cell? [110] <111> {110} (100)
(100)
Select all of the following statements that correctly describe a single crystal. - All unit cells have the same orientation. - Most crystalline solids are composed of a single crystal. - The periodic arrangement of atoms extends through the whole specimen. - Typically do not exist in nature.
- All unit cells have the same orientation. - The periodic arrangement of atoms extends through the whole specimen.
Select all of the following statements that correctly describe electronegativity: - The most electronegative atom is Helium. - Atoms that have high electronegativity will readily accept an electron to form a negatively charged ion. - The greater the difference in electronegativity between two bonded atoms, the more covalent the bond. - Within the Periodic Table, electronegativity increases in moving left to right and from top to bottom.
- Atoms that have high electronegativity will readily accept an electron to form a negatively charged ion.
Select all of the following statements that correctly describe electronegativity: - The most electronegative atom is Helium. - The greater the difference in electronegativity between two bonded atoms, the more covalent the bond. - Within the Periodic Table, electronegativity increases in moving left to right and from top to bottom. - Atoms that have high electronegativity will readily accept an electron to form a negatively charged ion.
- Atoms that have high electronegativity will readily accept an electron to form a negatively charged ion.
The atoms in a noncrystalline material are: - Bonded to their "nearest-neighbor" atoms by noncrystalline bonds. - Bonded to each other in such a way that no long-range order is created within the material. - Arranged in a lattice. - Situated in a repeating array over sub-Angstrom distances
- Bonded to each other in such a way that no long-range order is created within the material.
Select all of the following statements that correctly describe ionic bonds: - Bonding typically takes place between metallic and nonmetallic elements. - Electrons are shared between adjacent atoms. - Bond energies are relatively small. - One example is NaCl. - Bonding is directional.
- Bonding typically takes place between metallic and nonmetallic elements. - One example is NaCl.
Select all of the following statements that correctly describe the modulus of elasticity, E: - Values are typically highest for polymeric materials. - Can be calculated using the "strain offset" method. - Can be thought of as "stiffness". - A measure of the interatomic bonding forces. - Proportionality constant in Hooke's law.
- Can be thought of as "stiffness". - A measure of the interatomic bonding forces. - Proportionality constant in Hooke's law.
Select all of the following statements that correctly describe the concept of a unit cell. - Small geometric entities that are useful to describe the positions of atoms in a material. - Considered to be the basic structural unit of noncrystalline materials. - Can be thought of as a 3D "building block" of a lattice.
- Can be thought of as a 3D "building block" of a lattice. - Small geometric entities that are useful to describe the positions of atoms in a material.
Select all of the following statements that correctly describe plastic deformation in crystalline materials: - Involves only stretching of atomic bonds. - Caused by the motion of dislocations through a process known as "slip". - Corresponds to the net motion of a large number of atoms in response to an applied stress. - Deformation is completely reversible.
- Caused by the motion of dislocations through a process known as "slip". - Corresponds to the net motion of a large number of atoms in
Select all of the following statements that correctly describe plastic deformation in crystalline materials: - Involves only stretching of atomic bonds. - Corresponds to the net motion of a large number of atoms in response to an applied stress. - Caused by the motion of dislocations through a process known as "slip". - Deformation is completely reversible.
- Caused by the motion of dislocations through a process known as "slip". - Corresponds to the net motion of a large number of atoms in response to an applied stress.
Select all the following statements that correctly describe covalent bonds: - Electrons are shared between adjacent atoms. - Bonding is directional. - Bond energies are very small. - The number of covalent bonds that is possible for a particular atom is determined by the atom's atomic number. - Typical example is NaCl.
- Electrons are shared between adjacent atoms. - Bonding is directional.
Select all of the following statements that correctly describe x-rays: - Form of high-energy electromagnetic radiation. - Have wavelengths on the order of atomic spacings. - Are used to determine a solid's interplanar spacing.
- Form of high-energy electromagnetic radiation. - Have wavelengths on the order of atomic spacings. - Are used to determine a solid's interplanar spacing.
Select all of the following statements that correctly describe an amorphous material: - Lack long-range order. - Can be formed by slowly cooling a liquid substance to its solid state. - Typically composed of relatively complex atomic or molecular structures.
- Lack long-range order. - Typically composed of relatively complex atomic or molecular structures.
Metals, ceramics, and polymers are the three basic categories of materials. Select the following statements that are generally true regarding the different categories. - Polymers have better resistance to high temperatures than metals. - Metals and ceramics have better ductility than polymers. - Metals are typically better electrical conductors than ceramics and polymers. - Polymers and composites typically have lower densities than metals and ceramics. - Ceramics are very strong yet more brittle than metals and polymers.
- Metals are typically better electrical conductors than ceramics and polymers. - Polymers and composites typically have lower densities than metals and ceramics. - Ceramics are very strong yet more brittle than metals and polymers.
Select all of the following statements that correctly describe bonding energy: - Secondary bonds have lower bond energies than primary bonds. - E0 is the energy required to separate two atoms that are spaced r0 apart. - Materials with large bonding energies typically have low melting temperatures. - At room temperature, gases have larger bonding energies than solids. - The magnitude of bond energy depends on the bonding type within a material.
- Secondary bonds have lower bond energies than primary bonds. - E0 is the energy required to separate two atoms that are spaced r0 apart. - The magnitude of bond energy depends on the bonding type within a material.
Select all of the following statements that correctly describe elastic deformation: - Typically results in a plot of stress versus strain that is linear. - Can be described by Hooke's law. - Deformation in which stress and strain are proportional. - Deformation is permanent.
- Typically results in a plot of stress versus strain that is linear. - Can be described by Hooke's law. - Deformation in which stress and strain are proportional.
Select all of the following statements that correctly describe valence electrons: - Valence electrons occupy the outermost shell of an atom. - Valence electrons drift freely within most metals. - Valence electrons are the lowest energy electrons. - The number of valence electrons is given by the atom's atomic number. - Valence electrons participate in bonding between atoms to form different atomic and molecular structures.
- Valence electrons occupy the outermost shell of an atom. - Valence electrons drift freely within most metals. - Valence electrons participate in bonding between atoms to form different atomic and molecular structures.
Which of the following indicates a "family" of equivalent directions within a unit cell? - (110) - <100> - [110] - {111}
<100>
A material's "structure encompasses the following: -Molecules -Atoms -Electrons
All of the above
If a crystalline solid has a different electrical conductivity in the [100] and [111] directions, it is said to be: Anisotropic Subtropic Isotropic Entropic
Anisotropic
A cubic unit cell with atoms located at all 8 corners and a single atom at the center is representative of which crystal structure? BCC HCP FCC
BCC
A "smart" material is one that: - Can change its properties based on an environmental stimulus. - Got a 4.0 in high school. - Is used primarily for "S"cience, "M"echanical, or "Art" applications.
Can change its properties based on environmental stimulus
The following Callister figure illustrates which type of bonding: (Shared electron from hydrogen and carbon)
Covalent
Select all of the following statements that correctly describe plastic deformation: - Typically results in a plot of stress versus strain that is linear. - Deformation is permanent. - Deformation in which stress and strain are not proportional. - Can be accurately described by Hooke's law.
Deformation is permanent, Deformation in which stress and strain are not proportional
___________ are linear (one-dimensional) defects within crystalline materials which cause misalignment of nearby atoms. - Grain boundaries - Twin boundaries - Dislocations - Stacking faults
Dislocations
Which of the following is a consequence of the type of atomic bonding within most metals? - Low density - Poor electrical and thermal conductivity - High melting temperatures - Ductile failure at room temperature
Ductile Fracture at room temperature
The feature labelled as (1) in the following images indicates what? - Idealized caterpillar trapped in a sea of electrons - Extra half-plane of atoms - Extra plane of half-atoms - Slip plane
External half-plane of atoms
A cubic unit cell with atoms located at all 8 corners and the centers of all 6 faces is representative of which crystal structure? FCC BCC HCP
FCC
A "dogbone" specimen configuration is typically used for compression tests.
False
At the atomic scale, elastic deformation corresponds to breaking of interatomic bonds whereas plastic deformation corresponds to stretching of interatomic bonds.
False
Edge dislocations are considered to be two-dimensional defects while grain boundaries are one-dimensional defects
False
For an FCC crystal structure, h + k + l must be even for diffraction to occur.
False
Nanomaterials may be metallic or ceramic but never polymeric.
False
The three principal ways in which a load may be applied to a material are torsion, compression, and shear.
False
The SI unit for Young's modulus is: Pounds force (lbf) Gigapascals (GPa) Newtons (N) Newton-meters (N m)
Gigapascals (GPa)
The data contained in the following plot is related to which strengthening mechanism for crystalline metals: (Yield Strength vs diameter) Grain size reduction Solid-solution strengthening Recrystallization Strain hardening
Grain size reduction
Atoms located at external surfaces of a material are in a __________ energy state than the atoms at the interior of a material due to unsatisfied bonding conditions.
Higher
Ductile materials typically have __________ values of percent elongation compared with brittle materials. Lower Similar Higher
Higher
Images A and B illustrate the atomic structure of silicon dioxide (SiO2 or "silica"). Which structure would you expect to form for silica that has been rapidly cooled from a high-temperature liquid to a room-temperature solid?
Image A
During plastic deformation, the number of dislocations ______________ . - Increases - Decreases - Is constant
Increases
The following figure illustrates which type of bonding (NaCl)
Ionic
Substances in which the measured properties (e.g., stiffness) are independent of the direction of the measurement are referred to as: Anisotropic Entropic Isotropic Subtropic
Isotropic
The SI unit for engineering stress is:
Megapascals (MPa)
The following Callister figure illustrates which type of bonding: (Sea of valance electrons/ion cores)
Metallic
Grain boundaries are typically ________ chemically reactive than the grains themselves, due to atoms near the grain boundaries having less regular (and thus unsatisfied) bonds. -Less -More
More
Which of the following is a consequence of the type of atomic bonding within most ceramics? Low melting temperatures Poor electrical and thermal conductivity Ductile failure at room temperature Low density
Poor electrical and thermal conductivity
Grain boundaries within crystalline materials tend to ___________ the mobility of dislocations, which is why a material with larger grains is typically ___________ than a material with smaller grains. Reduce; weaker Increase; stronger Increase; weaker Reduce; stronger
Reduce; weaker
The following Callister figure illustrates which type of bonding (H2O)
Secondary (H-Bonding)
The combination of the preferred crystallographic plane and directions on that plane along which dislocation motion typically occurs is known as the: Stacking fault Slip system Slip direction Slip plane
Slip System
The data contained in the following plot is related to which strengthening mechanism for crystalline metals: (Tensile Strength vs. Nickel content (wt%)) Recrystallization Strain hardening Grain size reduction Solid-solution strengthening
Solid-solution strengthening
The data contained in the following plot is related to which strengthening mechanism for crystalline metals: (yield strength vs % Cold Work) - Strain hardening - Recrystallization - Solid-solution strengthening - Grain size reduction
Strain Hardening
Strain hardening is a phenomenon whereby a metal becomes ___________ as it is plastically deformed due to an increase in dislocation density within the material. (select up to 2 responses) Stronger Less ductile Softer Weaker
Stronger, Less Ductile
Alloys are typically ___________ than pure metals because impurity atoms within the metal's crystal structure impose lattice strains on the surrounding atoms which ultimately ___________ the mobility of dislocations. - Stronger; reduce - Weaker; reduce - Stronger; increase - Weaker; increase
Stronger; Reduce
Compared with the other classes of materials, metals have a relatively large number of different crystal structures because: - Metals contain more atoms. - The atoms in metals are typically smaller in size. - The bonds within metals are nondirectional. - The bonds within metals are ionic.
The bonds within metals are nondirectional
During a tensile test, the measured (raw) values of force versus elongation are dependent on specimen geometry, which makes it difficult to compare raw data collected from specimen of different sizes.
True
Most crystalline solids are polycrystalline, which means they are composed of many small crystals or "grains" that are separated by "grain boundaries".
True
Nanomaterials are typically classified not by their chemistry but by their length scale (ie., size).
True
Semiconductors have electrical properties that are intermediate between good electrical conductors (e.g., metals and metal alloys) and good electrical insulators (e.g., ceramics and polymers).
True
The structure and corresponding properties of a material is influenced by how it is processed.
True
Interfacial defects include which of the following: External surfaces Edge dislocations Twin boundaries Grain boundaries Screw dislocations
Twin boundaries, Grain boundaries, External surfaces
The "strain offset" method is often used to determine: Tensile strength Percent elongation Yield strength Young's modulus
Yield Strength
Which of the following indicates a single direction within a unit cell? [100] {111} (110) <110>
[100]
Which of the following indicates a "family" of equivalent planes within a unit cell? (111) [110] {100} <111>
{100}
