A5:Diffusion(Chapter 5) 6 points a) Due to charge neutrality no single vacancies can exist in an ion crystal.Name and explain two different defects,from which the charge neutrality in a crystal is preserved.(2 points) b) Sketch the ion conductivity o as a function of the temperature T and name the two occurring ranges.(4 points) A6:Crystal Plasticity (Chapter 6) 13 points a Draw a technical diagram of the nominal stress(schematic)over strain with continuous transition between elastic and plastic range.(1.5 points) b) Indicate and specify the five most important characteristics in this diagram.(2.5 points) c) Further,draw a qualitative diagram of the true stress over strain in the same diagram. (1 point) S To determine the uniform strain the Considere-criterion can be consulted.Derive the formula and depict it graphically.Explain the used formula signs.(6 points) e On which material parameters depend the critical resolved shear stress in bcc metals and in fcc metals?At which crystal structure(fcc or bcc)exist a clear temperature dependency of the critical shear stress and explain the reason briefly?(2 points) A7:Time-dependent Deformation(Chapter 6) 5.5 points Draw a schematic creep curve s(t)and creep rate curve (t)as a function of time for two different temperatures each(TI<T2).Mark unambiguously which temperature corresponds to which curve.Indicate and name the three characteristic parts of the creep curve.(5.5 points) 66 A5: Diffusion (Chapter 5) 6 points a) Due to charge neutrality no single vacancies can exist in an ion crystal. Name and explain two different defects, from which the charge neutrality in a crystal is preserved. (2 points) b) Sketch the ion conductivity σ as a function of the temperature T and name the two occurring ranges. (4 points) A6: Crystal Plasticity (Chapter 6) 13 points a) Draw a technical diagram of the nominal stress (schematic) over strain with continuous transition between elastic and plastic range. (1.5 points) b) Indicate and specify the five most important characteristics in this diagram. (2.5 points) c) Further, draw a qualitative diagram of the true stress over strain in the same diagram. (1 point) d) To determine the uniform strain the Considère-criterion can be consulted. Derive the formula and depict it graphically. Explain the used formula signs. (6 points) e) On which material parameters depend the critical resolved shear stress in bcc metals and in fcc metals? At which crystal structure (fcc or bcc) exist a clear temperature dependency of the critical shear stress and explain the reason briefly? (2 points) A7: Time-dependent Deformation (Chapter 6) 5.5 points Draw a schematic creep curve ε(t) and creep rate curve ε&( )t as a function of time for two different temperatures each (T1 < T2). Mark unambiguously which temperature corresponds to which curve. Indicate and name the three characteristic parts of the creep curve. (5.5 points)