Homework 4 PDF

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HOMEWORK 4 1. Calculate the energy for vacancy formation in silver, given that the equilibrium number of vacancies at 800°C (1073 K) is 3.61023 m-3. The atomic weight and density (at 800°C) for silver are, respectively, 107.9 g/mol and 9.5 g/cm3. 2. Gold has 5.82x108 vacancies/cm3 at equilibrium at 300 K. What fraction of the atomic sites is vacant at 600 K? 3. The density of a sample of FCC palladium is 11.98 g/cm3, and its lattice parameter is 3.8902 Å. Calculate a. the fraction of the lattice points that contain vacancies b. the total number of vacancies in a cubic centimeter of Pd. 4. A single crystal of a BCC metal is oriented so that [001] is parallel to the applied stress. If the critical resolved shear stress required for slip is 12,000 psi, calculate the magnitude of the applied stress required to cause slip to begin in 111 on (110), (011), and 101  . 5. Consider a metal single crystal oriented such that the normal to the slip plane and the slip direction are at angles of 60° and 35°, respectively, with the tensile axis. If the critical resolved shear stress is 6.2 MPa (900 psi), will an applied stress of 12 MPa (1750 psi) cause the single crystal to yield? If not, what stress will be necessary? 6. A single crystal of zinc is oriented for the tensile test such that its slip plane normal makes an angle of 65° with the tensile axis. Three possible slip directions make angles of 30°, 48°, and 78° with the same tensile axis. a. Which of these three slip directions is most favored? b. If plastic deformation begins at a tensile stress of 2.5 MPa (355 psi), determine the critical resolved shear stress....