Can we have an adiabatic process in a sealed metal container?
Adiabatic means that energy is transferred between the system and the surroundings only as work and not as heat.

Let's look at your process. You have a non-isothermal process, so $\Delta T_{sys} \ne 0$ for the process. An adiabatic process does not need to be isothermal, so this condition is okay. What makes your process non-adiabatic is the condition that constant temperature is somehow maintained (likely through a constant temperature bath which serves as the surroundings). This requires heat exchange between the system inside the metal container and the surroundings outside the container.

If you remove the constraint that the overall temperature is held constant, then you can have an adiabatic process.