12.16 Ag-W alloys (contact materials) and the mixture rule Silver-tungsten alloys are frequently used in heavy-duty switching applications (e.g., current-carrying contacts and oil circuit breakers) and in arcing tips. AgW is a two-phase alloy, a mixture of Ag-rich and W-rich phases. The measured resistivity and density for various AgW compositions are summarized in Table 2.12. a. Plot the resistivity and density of the AgW alloy against the W content (wt. \%) b. Show that the density of the mixture, d, is given by d1=wd1+wd1 where wa is the weight fraction of phase ,w is the weight fraction of phase ,da is the density of phase , and d is the density of phase . c. Show that the resistivity mixture rule is =ddw+djdw where is the resistivity of the alloy (mixture), d is the density of the alloy (mixture), and subscripts and refer to phases and , respectively. d. Calculate the density d and the resistivity of the mixture for various values of W content (in wt. \%) and plot the calculated values in the same graph as the experimental values. What is your conclusion? Table 2.12 Dependence of resistivity in Ag-W alloy on composition as a function of wt.\% W NOTE: = resistivity and d= density