Eng 45 Uc Merced

Front 1

If copper is stressed to just below its ultimate tensile strength, is all the deformation plastic is all the deformation elastic or is the deformation both plastic and elastic.

Back 1

Deformation before yield point is elastic and deformation after yield point is plastic the sum of the two will be the stress in this case.

Front 2

If a Metals subjected to a stress of 2E/1000 during a tensile test has it undergone any plastic deformation? (E =Young’s modulus)

Back 2

2E/1000~ .002 strain on stress strain graph. most metals begin to deform plastically but some may yeild before this point

Front 3

Is it true that Necking occurs in metals that are subjected to a stress-strain test in which true stress is plotted against true strain?

Back 3

Necking is real and observable and occurs in metals subject to a stress strain test weather or not true stress is plotted against true strain.

Front 4

Is the hardness exponent of some steels is equal to 0.15?

Back 4

Hardness exponent is not a term, HARDENING exponent is though.

Front 5

Is it correct that if material A has a higher stiffness than material B, material A must also have a higher proportional limit than material B?

Back 5

Where a materials yields is not related to its stiffness.

Stiffness: Initial Slope on stress strain graph

Yeild: length of linear portion of graph (elastic deformation portion)

Front 6

When materials are subjected to a tensile stress is the lateral strain is always negative?

Back 6

Some materials grow in diameter as they increase in length aka have a negative Poisson’s ratio. look at auxetic foam

Front 7

When metals are subjected to a tensile stress is the lateral strain is always positive?

Back 7

Metals all have a positive Poisson’s ratio. When length is increased by tensile stress the lateral strain is negative or the diameter is decreased.

Front 8

When materials are subjected to a tensile strain, is the lateral strain is always negative?

Back 8

tensile strain is change in length. lateral strain is change in diameter. You need tensile stress to create a lateral strain which may be positive or negative

Front 9

When metals are subjected to a tensile stress, is the strain is always proportional to the magnitude of the stress?

Back 9

True in ELASTIC CASES

Front 10

When materials are subjected to a compressive stress, the Young’s Modulus is always positive.

Back 10

YES Youngs Modulus Always Positive

Front 11

Which recrystallization temperature is higher the recrystallization temperatureof brass or the recrystallization temperature of copper

Back 11

Pure metals recrystallize faster than alloys so recrystallization temperature of brass is higher because it is an alloy

Front 12

Which is lower, the recrystallization temperature of bronze or the recrystallization temperature of copper.

Back 12

Pure metals recrystallize faster than alloys so recrystallization temperature of copper is lower because it is a pure metal

Front 13

Can Recrystallization occur at room temperature?

Back 13

Yes, recrystallization can occur at room temperature such as metals that have a low melting point.

Front 14

When a cold worked material is annealed. Is the microstructure at time t2 coarser than the microstructure at time t1? if t2 > t1.

Back 14

annealing is reheating the material and in recrystallization the grains to re form in a finer and more equal orientation than in recovery

Front 15

Is the planar density of the close-packed planes in iron at room temperature is greater than the planar density of (1 -1 0) iniron at room temperature?

Is the planar density of the close-packed planes in iron at room temperature is less than the planar density of (1 -1 0) in iron atroom temperature?

Back 15

Iron at room temperature is BCC, and therefore has no close-packed planes.

Front 16

Is the planar density of (111) in iron at room temperature is greater than the planar density of (110)in iron at roomtemperature?

Is the planar density of (111) in iron at room temperature is greater than the planar density of (1 1 0) in iron at roomtemperature?

Back 16

In a cubic crystal, planes (110) and 1 10 are in the same family, and are equivalent.()

Front 17

The planar density of (111) in iron at room temperature is less than the planar density of (1 1 0) in iron at roomtemperature.

Back 17

correct.

Front 18

sketch the (110) plane.

Back 18

Front 19

sketch the (111) plane.

Back 19

Front 20

Does the atom in the middle of the unit cell in BCC structure lie on the (111) plane?

Back 20

the (111) plane in diagram can be constructed by taking the (110)plane, maintaining the intercepts with the x- and y- axes, and tilting it back so that itintersects the z-axis.When the (110) plane is tilted in the way, it will no longer pass through the center of theunit cell, and so the atom at the middle of the unit cell cannot lie on the (111) plane.

Front 21

Is the Burgers vector of an edge dislocation is normal to the dislocation line and normal to the slip plane?

Back 21

The Burgers vector of an edge dislocation lies normal to the dislocation line and lies parallel to the slip plane.

Front 22

Is the Burgers vector of a screw dislocation is normal to the dislocation line and parallel to the slip plane?

Back 22

The Burgers vector of a screw dislocation is parallel to the dislocation line.

Front 23

When a screw dislocation enables slip in a single crystal, does the dislocation line remains in the slip plane.

Back 23

YES!

Front 24

Do BCC crystals not contain dislocations?

Back 24

All crystals have dilsocations

Front 25

Do fine-grained samples of γ-iron contain fewer dislocations than coarse-grained samples of γ-iron?

Back 25

The grain size does not affect the number of dislocations.

The grain size affects the mobility of dislocations.

Front 26

When x-ray diffraction patterns of Cu and Al are collected under identical conditions, are the reflection from {100} in Cuis more intense than the reflection from {111} in Al?

Back 26

Cu and Al are FCC metals.

h,k,l must be all even or all odd to have any intensity. So Al will have reflection while Cu wont.

Front 27

Is it true that if element A has the same atomic radius as element B at room temperature, then the solubility of A in B is the sameas the solubility of B in A at room temperature?

Back 27

radius is not the only factor to solubility

Front 28

Will stacking faults in HCP crystals change the structure locally to BCC?

Back 28

Stacking faults in HCP crystals change the structure locally to FCC not BCC.

Front 29

Is the activation energy for vacancy creation in a solid is an increasing function of temperature?

Back 29

concentration of vacancies depends on temperature not activation energy for vacancy creation.