If you think the statement is true,write the letter "T";otherwise, write ncrease as the atomic elements increase in a given ial exhibits an endur ce limit which m ns that the material can be cycled continuously without fracturing at any stress below the endurance limit. 4.Six parameters are needed to describe a crystal system,including three angles and three lattice ram Solid tend to deform in the direction along the planes that are the most closely packed. In an interstitial solid solution,the solute atoms and the solvent atoms are of similar size. > Steelmaking is made possible because of the formation of a substitutional solid solution. Grain boundaries improve movement of dislocations through a solid. 9 The fatigue failures have occurred under such conditions when the stresses developed were below the ultimate stress and frequently below the yield strength. 10.Insulating materials have high thermal conductivities and low thermal resistance. 11. Not all materials produce stress-strain diagrams on which there is a clear indication of the start of yicd th oisncrasd nsucseset yield strength isexpreeas the stic limit. nen a piece or mate al is subjected to a load,it will deform in on of the load only. 13. 14.M m ser anical properties rank highest in importance when selecting materials for many etals will experience ductile failures with much greater absorption of energy b e critical temperature to the followin stal s stems are ther an systems?What are the three types of unit cell that aton spelling and abbreviation are required for each type)(3points) 2.What are the two methods of measuring ductility?Use formula to express the corresponding methods and indicate the meaning of each symbol in the formula.Explain how the value of ductility can be used to distinguish a ductile material from a brittle material.(3points) 3. when it is heated deliberately?What are the What are the two factors that should be considered in creep forming?(lpoints) 策6而 第 6 页 contain only single bonds. V. True or false questions. If you think the statement is true, write the letter “T”; otherwise, write the letter “F” (15points) 1. Two electrons can exist in the same orbital if they have the same spins. 2. The ionization potential increase as the atomic numbers of the elements increase in a given periodic group. 3. A material exhibits an endurance limit, which means that the material can be cycled continuously without fracturing at any stress below the endurance limit. 4. Six parameters are needed to describe a crystal system, including three angles and three lattice parameters. 5. Solid tend to deform in the direction along the planes that are the most closely packed. 6. In an interstitial solid solution, the solute atoms and the solvent atoms are of similar size. 7. Steelmaking is made possible because of the formation of a substitutional solid solution. 8. Grain boundaries improve movement of dislocations through a solid. 9. The fatigue failures have occurred under such conditions when the stresses developed were below the ultimate stress and frequently below the yield strength. 10. Insulating materials have high thermal conductivities and low thermal resistance. 11. Not all materials produce stress-strain diagrams on which there is a clear indication of the start of yield as the load is increased. In such case, off set yield strength is expressed as the elastic limit. 12. When a piece of material is subjected to a load, it will deform in the direction of the load only. 13. Designers must consider creep strength as a basis for a structural design when a part is subjected to a sustained load in service. 14. Mechanical properties rank highest in importance when selecting materials for many applications. 15. In impact testing of metals, metals will experience ductile failures with much greater absorption of energy below the critical temperature. VI. Give a simple answer to the following questions (10points) 1. How many crystal systems are there? How many patterns can atoms form with these crystal systems? What are the three types of unit cell that atoms form with cubic crystal system? (Note: full spelling and abbreviation are required for each type) (3points) 2. What are the two methods of measuring ductility? Use formula to express the corresponding methods and indicate the meaning of each symbol in the formula. Explain how the value of ductility can be used to distinguish a ductile material from a brittle material. (3points) 3. What thermal effects does a metal rod exhibit when it is heated deliberately? What are the corresponding properties for describing the effects? (3points) 4. What are the two factors that should be considered in creep forming? (1points)