北京化工大学2008——2009学年第一学期
《材料导论I》（高材、生材）期末考试试卷标准答案课程代码 M S E 2 0 2 0 1 T
制订：赵静、刘玲，审校：邓建平、刘莲英
材料科学与工程学院
I. Choose a suitable classification from group I to group II. ( 10 points, 0.5pt/Q)
Group II
a.metal: 2,5,7,9
b.polymer: 3,8,10,18
c.ceramic: 6,12,13,15
posite: 1,4,16,17
e.other materials: 11,14,19,20
II. Choose the BEST TERM to match the definition and translate the selected term into Chinese. (10 points, 1pt/Q)
1.G) M ixture 混合物
2.C) Allotropy同素异形体
3.A) Life Cycle Analysis环境协调性评
价，材料生命周期性评价
4.J) Electronegativity电负性
5.D) Failure破坏
6.H) Resolving Power分辨率
7.P) Spectroscopy光谱学
8.N) Transmission electron microscope透
射电子显微镜
9.S) Densification致密化
10.T) Anisotropy各向异性
III. Choose the correct answer to the following questions (35 points, 1pt/Q)
1. A
2. D
3. C
4. B
5. C
6. D
7. B
8. D
9. C
10. C
11. A
12. C 13. C
14. B
15. C
16. D
17. B
18. D
19. A
20. D
21. D
22. C
23. C
24. B
25. B
26. C
27. C
28. A
29. C
30. C
31.A,B,C
32. C
33. B
34. D
35. D
IV. Choose a correct word or phrase according to the basic concepts and write it in the space provided. ( 10 points, 1pt/blank)
1.transfer or swap (transferring or swapping), share (sharing)
2.thermoplastics and thermosets (thermoplastic plastics and thermosetting plastics)
3.monomers
4.point, line (dislocation), area
5.% elongation (percent elongation), % reduction in area (percent reduction in area)
6.plastic
7.ductile
8.Fe3C
9.powdered metals (powdered metallurgy, sintered metals)
10.<2% (less than 2%), 2-4%
11.how the atoms/ions are stacked in the microstructure (or the stacking of atoms in the microstructure)
12.sintering
13.the cross-sectional areas over which a load can be applied.
14.purity
V. True or false questions. If you think the statement is true, write the letter “T”; otherwise, write the letter “F”. (12 points, 1pt/Q)
1.T
2. F
3. F
4. F
5. F
6.T
7. F
8. F
9. F
10.T
VI. Give a simple answer to the following questions. (26 points)
1. (2points)
The two basic forms of solids are amorphous and crystalline.
2.(2points)
The following five factors can influence the diffusion of atoms, molecules, or ions, including
1)Temperature which affects the rate of diffusion
2)Type of bonding of the matrix atoms: strong bonding takes more energy to break the bonds
3)Size of atoms: smaller atoms have a better chance of diffusion through a structure of larger atoms
4) a lattice structure that contains loosely packed atoms will offer less resistance to diffusing atoms than
one whose structure contains tightly packed atoms
5)Time: sufficient time for diffusion to take place
The students can choose any two of the abovementioned five factors.
3. The specimens of TEM should be very thin, while that of SEM should be electrically conductive.
4. The bimetallic strip must be made of two metals which are different in the coefficient of thermal expansion, the two metals will have different amount of thermal deformation when they are subjected to temperature change. The bimetallic strip bonded together thus will bend with a temperature change, which makes electrical contact with a switch.
5. Ductile fracture is preferred in most engineering applications due to that brittle fracture is a sudden fracture without any warning beforehand. A brittle material shows little evidence of forthcoming fracture by yielding, whist a ductile material, by yielding slightly, can relieve excess stress that would ultimately cause fracture. Therefore, ductile fracture can avoid catastrophic sudden fracture which brittle fracture normally occurs.
6. The forming conditions of the substitutional solid solution include 1) The solute atoms and the solvent atoms are of similar size. Specifically, the size of their atoms does not differ by more than 15%. 2) Their electron configurations are comparable. 3) They have a common crystalline structure.
7. Dislocations (or Line defects) have a great deal to do with the strength of a solid. An abundance of line defects (dislocations) strengthen the materials because that mutual interference in their movement through crystal prevents the planes of atoms from slipping. The presence of a few dislocations increases the ductility of
a crystalline solid.
8. A: brittle failures; B: mixed failures (the mixture of brittle and ductile failures); C: ductile failures.
The impact energy increases with temperature. When a material undergoes brittle failure at low temperature, it absorbs little amount of energy. In contrast, a material undergoes ductile failure above some critical temperature, it has much greater absorption of energy.
9. (1) Curve a is the stress-strain curve of ceramic, whilst curve b is that of metal.
(2) c: elastic region; d: plastic region; e: yield point or yield strength; f: tensile strength or ultimate strength.
(3) The modulus of elasticity of curve a is greater than that of curve b. The higher the modulus of elasticity is, the greater the stiffness of the material is, the stronger the interatomic bonding forces in a material are.
