※ [本文轉錄自 NTUMSE-97 看板] 作者: dpks6512 (小捲) 看板: NTUMSE-97 標題: [情報] 材導期中考古題 時間: Sat Nov 8 14:23:45 2008 Introduction of the Materials Science & Engineering Midterm 11/12/2002 There are 31 questions. Each question carries the same points(3%) except those marked in the question. 1. Briefly discuss the classification of materials and their corresponding properties.(5%) 2. About atomic bonding in solid (1) Briefly cite the main differences between the three primary interatomic bonds. (2) Draw the figure illustrating the dependence of repulsive, attractive, and net forces on interatomic separation for two isolated atoms. Define and indicate the equilibrium spacing of two isolated atoms on the figure. 3. 本題有圖，所以跳過，不過考的是hexahonal unit cell的Miller-Bravais跟 indices for direction (兩小題，各三分) 4. Iron exhibits a BCC structure with a lattice constant of 0.2866nm. (1) Calculate the atomic radius of iron atoms. (2) Determine the linear density for ﹝100﹞ direction. (3) Determine the planar density for (100) plane. 5. About crystalline defects (1) Compare and contrast substitutional and interstitial solid solutions. (2) Briefly discuss how vacancies affect the properties of materials. (3) Cite the factors that determine the solubility of solute in a solid solution. (4) Compare and contrast edge and screw dislocations.(5%) (5) Briefly describe a twin and a twin boundary. 6. About grain boundary (1) Briefly discuss the characteristics of a grain boundary.(5%) (2) Determine the ASTM grain size number if 100 grains per square inch are measured at a magnification of 50. 7. About diffusion (1) Write down the equation of Fick's second diffusion law, explain the physical meaning for each parameter in the equation. (2) Compare and contrast substitutional diffusion and interstitial diffusion. (3) For the diffusion of silver atoms in a fine-grained silver and a coarse-grained silver, which one has the higher diffusivity? Why? (4) Cite the purpose of carburization for carbon steels. Can the Fick's first law apply to the problem of carbuization? Why? (5) Briefly explain the strong dependence of the diffusivity on temperature. 8. About the mechanical preperties of metals (1) Draw the stress-strain curve for a metal subjected to tensile test. Cite and indicate on the stress-strain curve the materials properties measured. (2) Explain the phenomena of necking. (3) A cylindrical specimen of steel having an original diameter of 12.8mm is tensile tested to fracture and found to have an engineering ultimate tensile strength of 460 MPa. If its cross-sectional diameter at fracture is 10.7 mm, determine the ductility in terms of percent reduction in area and the true stress at fracture. (4) Briefly discuss the hardness of a metal. 9. About plastic deformation (1) What is the slip system for a metal? Write three slip systems for a FCC crystal. (2) What are the deformation mechanisms for a metal deformed at room temperature? (3) Consider a single crystal of silver oriented such that a tensile stress is applied along a [001] direction. If slip occurs on a (111) plane and in a [0-11] direction, and is initiated at an applied tensile stress of 1.1 MPa, compute the critical resolved shear stress. (4) Briefly explain how dislocations are involved in each of the strengthening techniques including grain boundary strengthening, solid solution strengthening and strain hardening.(5%) 10. About annealing (1) What is the driving force for recrystallization and for grain growth, respectively? (2) Cite the factors determining the recrystallization temperature of a metal. (3) Briefly explain the Chinese saying "打鐵趁熱". ------------- 第九題第三小題，我不知道怎麼把1上面加上-，不過想必大家都看的懂。 如果你看不懂題目的時候...有可能是我打錯＝　＝ 看不懂就提出來吧，不會的問題也提出來，大家可以討論。 附註: 考完試沒事做?? 來練舞阿!! 宅在宿舍沒事幹?? 來練舞阿!! 每天只會讀書有甚麼用?? 來練舞阿!! 擔心你肢體不協調又怎樣?? 來練舞阿!! 材料之夜男舞歡迎你 ^^ 負責人: 陳家昇 --

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