Material science question Consider a box containing an imper

Material science question

Consider a box containing an impermeable partition that divides the box into equal volumes as shown below. On one side, we have pure argon gas; on the other side, we have pure helium gas. Explain what will happen when the partition is opened. What will happen if we replace the Ar side with a single Cu crystal and the He side with a single Ni crystal?

Solution

Before the partition is opened, one compartment has no argon and the other has no helium (i.e., there is a concentration gradient of Ar and He). When the partition is opened, Ar atoms will diffuse toward the He side, and vice versa.

If we open the hypothetical partition between the Ni and Cu single crystals at room temperature, we would find that, similar to the Ar/He situation, the concentration gradients exist but the temperature is too low to see any significant diffusion of Cu atoms into Ni single crystal and vice-versa.