材料科学与工程基础英文版试题(共4页)

1、材料科学与工程基础”考试试题 英文原版教材班（注：第1、2、3题为必做题；第4、5、6、7题为选择题，必须二选一。共100分）1. Glossary (2 points for each) 1) crystal structure: The arrangement of the atoms in a material into a repeatable lattice. 2) basis (or motif): A group of atoms associated with a lattice. 3) packing fractor: The fraction of space in a u

2、nit cell occupied by atoms.4) slip system: The combination of the slip plane and the slip direction. 5) critical size: The minimum size that must be formed by atoms clustering together in the liquid before the solid particle is stable and begins to grow.6) homogeneous nucleation: Formation of a crit

3、ically sized solid from the liquid by the clustering together of a large number of atoms at a high undercooling (without an external interface). 7) coherent precipitate: A precipitate whose crystal structure and atomic arrangement have a continuous relationship with matrix from which precipitate is

4、formed. 8) precipitation hardening: A strengthening mechanism that relies on a sequence of solid state phase transformations in a dispersion of ultrafine precipitates of a 2nd phase. This is same as age hardening. It is a form of dispersion strengthening. 9) diffusion coefficient: A temperature-depe

5、ndent coefficient related to the rate at which atom, ion, or other species diffusion. The DC depends on temperature, the composition and microstructure of the host material and also concentration of the diffusion species. 10) uphill diffusion: A diffusion process in which species move from regions o

6、f lower concentration to that of higher concentration. 2. Determine the indices for the planes in the cubic unit cell shown in Figure 1. (5 points)Fig. 1Solution: A(-364), B(-340), C(346).3. Determine the crystal structure for the following: (a) a metal with a0 = 4.9489 Å, r = 1.75 Å and o

7、ne atom per lattice point; (b) a metal with a0 = 0.42906 nm, r = 0.1858 nm and one atom per lattice point. (10 points) Solution: (a)fcc; (b) bcc.4-1. What is the characteristic of brinell hardness test, rockwell hardness test and Vickers hardness test? What are the effects of strain rate and tempera

8、ture on the mechanical properties of metallic materials? (15 points) 4-2. What are the effects of cold-work on metallic materials? How to eliminate those effects? And what is micro-mechanism for the eliminating cold-work effects? (15 points)5-1. Based on the Pb-Sn-Bi ternary diagram as shown in Fig.

9、 2, try to (1)Show the vertical section of 40wt.%Sn; (5 points)(2) Describe the solidification process of the alloy 2# with very low cooling speed (including phase and microstructure changes); (5 points)(3)Plot the isothermal section at 150oC. (5 points)Fig. 25-2. A 1mm sheet of FCC iron is used to

10、contain N2 in a heated exchanger at 1200oC. The concentration of N at one surface is 0.04 atomic percent and the concentration at the second surface is 0.005 atomic percent. At 1000 oC, if same N concentration is demanded at the second surface and the flux of N becomes to half of that at 1200oC, the

11、n what is the thickness of sheet? (15 points)6-1. Supposed that a certain liquid metal is undercooled until homogeneous nucleation occurs. (15 points)(1) How to calculate the critical radius of the nucleus required? Please give the deduction process.(2) For the Metal Ni, the Freezing Temperature is

12、1453°C, the Latent Heat of Fusion is 2756 J/cm3, and the Solid-liquid Interfacial Energy is 255´10-7 J/cm2. Please calculate the critical radius at 1353°C. (Assume that the liquid Ni is not solidified.)6-2. Fig.3 is a portion of the Mg-Al phase diagram. (15 points)(1) If the solidific

13、ation is too rapid, please describe the solidification process of Mg-10wt%Al alloy.(2) Please describe the equilibrium solidification process of Mg-20wt%Al alloy, and calculate the amount of each phase at 300°C. Fig. 3 7-1. Figure 4 shows us the Al-Cu binary diagram and some microstructures fou

14、nd in a cooling process for an Al-4%Cu alloy. Please answer following questions according to this figure. (20 points) Fig. 4(1)What are precipitate, matrix and microconstituent? Please point them out in the in the figure and explain. (2)Why is need-like precipitate not good for dispersion strengthen

15、ing? The typical microstructure shown in the figure is good or not? why? (3)Please tell us how to obtain the ideal microstructure shown in this figure. (4)Can dispersion strengthened materials be used at high temperature? Please give the reasons (comparing with cold working strengthening)7-2. Please

16、 answer following questions according to the time-temperature-transformation (TTT) diagram as shown in Fig. 5. (20 points) (1)What steel is this TTT diagram for? And what means P, B, and M in the figure? (2)Why dose the TTT diagram exhibits a C shape? (3)Point out what microconstituent will be obtained after austenite is cooled according to the curves I, II, III and IV. (4)What is microstructural difference betw