Q2 The ends of a cylindrical rod 6.4 mm in diameter and 250 mm long are mounted between fixed supports. The rod is stress free at room temperature [20°C (68"F)); upon cooling to -40°C, a maximum thermally induced tensile stress of 125 MPa is possible. Of which of the following metals or alloys may the rod be fabricated: aluminum, copper, brass, 1025 steel, and tungsten? Why? [20 Marks]