QUESTIONS 6.1 What information may be obtained from an equilibrium diagram? 6.2 Explain the importance of equilibrium diagrams in the development of new alloys. 6-3 Platinum and gold are completely soluble in both the liquid and solid states. The melting point of platinum is 3225°F and that of gold is 1945°F. An alloy con- taining 40 percent gold starts to solidify at 2910°F by separating crystals of 15 percent gold. An alloy containing 70 percent gold starts to solidify at 2550°F by separating crystals of 37 percent gold. a Draw the equilibrium diagram to scale on a piece of graph paper and label all points, lines, and areas. b For an alloy containing 70 percent gold (1) give the temperature of initial solidification; (2) give the temperature of final solidification; (3) give the chemical composition and relative amounts of the phases present at 2440°F; (4) draw the cooling curve. 6.4 Bismuth and antimony are completely soluble in both the liquid and solid states. a Check the crystal-structure factor and calculate the relative-size factor for these metals. b Bismuth melts at 520°F and antimony melts at 1170°F. An alloy containing 50 percent bismuth starts to solidify at 940°F by separating crystals of 90 percent antimony. An alloy containing 80 percent bismuth starts to solidify at 750°F by separating crystals of 75 percent antimony. 1 Draw the equilibrium diagram to scale on a piece of graph paper labeling all lines, points, and areas. 2 For an alloy containing 40 percent antimony, (a) give the temperature of initial solidification; (b) give the temperature of final solidification; (c) give the chemical composition and relative amounts of the phases present at 800°F; (d) draw the cooling curve.