A diffusion couple of two metals, A and B, was fashioned as shown in Figure 5.1. After a 26 hour heat treatment at 1040C (and subsequent cooling to room temperature) the concentration of A is 4.0wt% at the 12 -mm position within metal B. If another heat treatment is conducted on an identical diffusion couple, only at 731C for 26 hours, at what position (in mm) will the composition be 4.0wt%A ? The preexponential and activation energy values for the diffusion of A in B are 2.4104m2/s and 154kJ/mol, respectively. mm