Q: The diffusion coefficient for copper in aluminium at 500°C and 600°C are 4.8 × 10⁻¹⁴ m²/s and 5.3 × 10⁻¹³ m²/s respectively. What is the approximate time at 500°C that will produce the same diffusion result (in terms of concentration of copper at some specific point in aluminium) as 10 h heat treatment at 600°C?