Solution This problemasks us to determine the values of Qa and Do for the diffusion of Fe in Cr from the plot of log D versus 1/T. According to Equation log D = log Do - 2.3R (1) the slope of this plot is equal to - -(rather than - -since we are using log D rather than In D) and the intercept at 1/T = 2.3 R R 0 gives the value of log Do. The slope is equal to A (log D) log D - log D2 slope = A( ) T - T . Taking 1/T1 and 1/T2 as 0.65 x 10-3 and 0.60 * 10-3 K-1, respectively, then the corresponding values of D, and D2 are 2.81 x 10-16 and 1.82 x 10-15, as noted in the figure below. 1.82 x 10-13 10-15 Diffusion coefficient (m2/s) 2.51 x 10-16 10-16 0.55 0.60 0.65 0.70 Reciprocal temperature (1000/K)