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Question 1 (a) (i) List and briefly explain the four components of the discipline of materials science and engineering in a linear relationship. [4] (ii) Using a flowchart, classify engineering materials, indicating the types of polymers. [5] SECTION A (b) The ionic radii and coordination number of NaCl is 0.414 -0.732 and 6 respectively. Using the data below, show that FeO has the structure of NaCl. [8] Ion (cation/anion) A1³+ Fe3+ 0²- CI F Fe2+ Ionic radius (nm) 0.053 0.069 0.140 0.181 0.133 0.077 (c) Determine the Miller indices for the directions in the cubic unit cell shown below (Fig. Q1): [8] 11 Figure Q1
Question 2 (a) (i) List and briefly explain the six properties of solid materials. [6] (ii) Using a flowchart, classify metals and alloys. [6] (b) BCC lithium has a lattice parameter of 3.5089 x 10-10 m and contains one vacancy per 200 unit cells. Calculate: (i) the number of vacancies per cubic metre and (ii) the density of lithium. Show that the APF for a FCC crystal structure is 0.74. (c) [2] [3] [8] Question 3 (a) Sketch and label the typical stress-strain curve, identify and explain all the major points on the curve. [7] (b) The number of vacancies in a material is related to the temperature by an Arrhenius equation. If the fraction of lattice points containing vacancies is 8 x 105 at 600 °C, determine the fraction at 1000 °C. [R = 8.314 J/K.mol]. [9] The diffusion coefficient for Cr in Cr₂O3 is 6 x 10-¹9 m²/s at 727 °C and is 1 x 10-13 m²/s at 1400 °C. Calculate the activation energy and the diffusion constant Co. [9]