Exercise 4 Look at the Cu-Ni alloy in fig. 7.1a. After 700 hours of heat treatment at 1100 C is the concentration of Cu 2.5 wt%, 3 mm below the surface of Ni. What temperature is required to achieve the same concentration 2 mm from the surface? D0 and Qd for Cu in Ni are given in tab. 7.2.