chapter 7 dislocations and strengthening mechanisms
chapter 7 questions and problems
1、chapter 7 questions and problems
chapter 8 phase diagram
chapter8 questions and problems
1、chapter8 questions and problems
chapter 9 phase transformations
chapter9 questions and problems
1、chapter9 questions and problems
chapter9 questions and problems
1、one question one point
materials science & engineering final exam
materials science & engineering final exam
1、atomic weight (a) of an element corresponds to the weighted average of the atomic masses of the atom’s naturally occurring ___________. a、ions b、charges c、isotopes d、particles
2、which of the following is not an example of primary bonding? a、van der waals b、ionic c、covalent d、metallic
3、covalent bonding occurs as a result of _________ sharing. a、proton b、electron c、neutron d、none of them
4、bonds in most metals are referred to as ______. a、directional b、ionic c、non-directional d、covalent
5、if the electron configuration of fe is 1s2 2s2 2p6 3s2 3p6 3d6 4s2, then the electron configurations for the fe3 is 1s2 2s2 2p6 3s2 _____. a、3p6 3d5 b、3p8 3d3 c、3d6 3p5 d、3d6 4s2 4p3
6、how many atoms does the face centered cubic unit cell contain? a、two b、four c、three d、one
7、a ______ material is one in which the atoms are arranged in a periodic array over large atomic distance. a、amorphous b、ceramic c、polymer d、crystalline
8、the crystal structure of cu is . a、simple cubic b、fcc c、bcc d、hcp
9、the coordination number of bcc crystal structure is a、2 b、4 c、6 d、8
10、the atomic packing factor for fcc is a、0.74 b、0.68 c、0.8 d、1
12、substitutional atom (impurity) is an example of ______. a、point defect b、linear defect c、planar defect d、bulk defect
13、one explanation for why graphite powder acts so well as a “solid lubricant” is a、carbon atoms in graphite are covalently bonded within planar layers but have weaker secondary bonds between layers defect b、finely-powdered carbon has many unsatisfied bonds at the particle surfaces, which act as a “sea of electrons” to cause lubrication c、when crushed into a fine powder, graphite establishes a “polar” distribution of charge, leading to coulombic repulsion between powder particles d、none of above
14、a ____ may form when impurity atoms are added to a solid, in which case the original crystal structure is retained and no new phases are formed. a、defect b、solid solution c、chemical compound d、metal
15、edge and screw dislocations differ in what way? a、1 magnitude of their burgers vectors b、line direction is straight (edge) or curved (screw) c、angle between burgers vector and line direction d、none of above
16、vacancy diffusion is usually interstitial one. a、slower than b、faster than c、similar to d、equal to
17、during elastic deformation, a metal experiences . a、necking b、bond breaking c、bond stretching d、fracture
18、hardness is a measure of . a、resistance to surface penetration b、resistance to deformation in the elastic limit c、resistance to formation of circular indentations d、none of above.
19、materials with the greatest toughness . a、have the greatest ductility b、have the highest young's modulus c、have a combination of strength and ductility d、none of above
20、structural engineering steels are sometimes found to be brittle . a、at high values of strain b、at low ambient temperatures c、at moderate concentrations of carbon d、at high ambient temperatures
21、in a pure metal the mechanisms of strengthening available are: a、solid solution hardening and ageing b、reduction in grain size and strain hardening c、a and b together d、reduction in grain size only
22、refer to the phase diagram of sn-pb alloy for questions 22– 25: the phase diagram of sn-pb alloy is called . a、isomorphous phase diagram b、peritectic phase diagram c、eutectoid phase diagram d、eutectic phase diagram
23、the phase(s) present for a 85 wt% sn–15 wt% pb alloy at 200 °c is (are) ____________. a、b l b、b c、a b d、a l
24、the a phase indicates ______. a、sn rich phase b、sn and pb rich c、eutectic reaction d、pb rich phase
25、the boundary above which only liquid phase exist is called _________. a、liquidus b、solidus c、eutectic line d、y-axis
26、a copper-nickel alloy is high-temperature heat treated; the diffusion of cu into ni and ni into cu regions is referred to as _____________________. a、vacancy diffusion b、interstitial diffusion c、bonding d、inter-diffusion
27、which of the following metal has lower value of diffusion coefficient in silicon at about 550 °c and is preferred as interconnects in integrated circuits. a、silver b、copper c、aluminium d、gold
28、the driving force for steady-state diffusion is the __________. a、(a) concentration gradient b、(b) electric field c、(c) temperature d、(d) atomic oscillations
29、______________________ is the property by virtue of which a body tends to regain its original shape and size when external forces are removed. a、strain b、elasticity c、hardness d、deformation
30、engineering stress-strain curve and true stress-strain curve are equal up to a、proportional limit b、elastic limit c、yeild point d、tensile strength point
31、in a plain steel that contains 0.2 percentage carbon, we should expect: a、a eutectoid steel b、a hypereutectoid steel c、a 25% pearlite and 75% pro-eutectoid ferrite d、a 75% pearlite and 25% pro-eutectoid ferrite
32、the maximum solubility of c in γ-austenite - solid solution is . a、0.77 b、2.14 c、3.4 d、6.67
33、we have an annealed carbon steel which has hardness of 150hbs. suppose we know the hardness of pearlite is 200hbs and the hardness of ferrite is 80hbs, determine the carbon amount of this steel. a、(a) 0.45% b、(b) 0.8% c、(c) 1.2% d、(d) 0.2%
34、which of the following plane has the highest planar density for fcc. a、(111) b、(100) c、(110) d、(123)
35、strain hardening is also named as . a、hot working b、metal forming c、work hardening d、annealing
36、strength is increased by making dislocation motion . a、fast b、constant c、difficult d、stop
37、during heat treatment of steel, austenite transforms into martensite by . a、annealing b、austenitizing c、quenching d、normalizing
38、heating the cold-worked metal progresses in three stages: a、recrystallization, recovery, grain growth b、recovery, recrystallization, grain growth c、recovery, crystallization, recrystallization d、recovery, crystallization, grain growth
39、in the as-quenched state, martensite is very hard and so brittle that a heat treatment known as must be accomplished sequently. a、normalizing b、annealing c、tempering d、austempering
40、the heat-treatable aluminum alloy can be strengthened by . a、solution heat treating b、precipitation heat treating c、both (a) (b) d、none of above
41、the cooling rate for normalizing is faster than that of annealing
42、in a plain carbon steel, bainite can be produced by continuous cooling
43、the driving force behind the recrystallization process is the stored energy of the material
44、steels are readily used after the heat treatment of quenching
45、a steel should be used below its ductile-to-brittle transition temperature
46、martensite is a product of a diffusionless transformation
47、thermosetting plastics are those that do not soften when heated
48、to obtain an steel with fine pearlite we perform the commercial heat treatment known as total annealing
49、martempering needs to be performed during quenching thick sections of steels to avoid surface crack formation