MECH 210 – Materials Science and Engineering Problem Set 05, fall Semester 2008 Due Monday (10/13) 1. Calculate the number of vacancies per cubic millimeter in gold at 900 ° C. The energy for vacancy formation is 0.98 eV/atom. Furthermore, the density and atomic weight for Au are 18.63 g/cm 3 (at 900 ° C) and 196.9 g/mol, respectively. 2. Niobium forms a substitutional solid solution with vanadium. Compute the number of niobium atoms per cubic centimeter for a niobium-vanadium alloy that contains 24 wt% Nb and 76 wt% V. The densities of pure niobium and vanadium are 8.57 and 6.10 g/cm 3 , respectively. 3. Compute the magnitude of the Burger’s vector for a pure BCC iron at room temperature. 4. Given the photomicrograph of an alloy taken at a magnification of 200×, determine the ASTM grain size number. 5. Using the same photomicrograph in Problem 4, determine (a) the average grain size in millimeters and (b) the total grain boundary area ( in mm2) per cubic millimeter (mm3) using the intercept method.
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