If stearic acid be used to milling and mechanical alloying of 1 wt% pure Aluminium powder, should the degassing be done after milling (by planetary milling)?
The stearic acid can be removed from the powder after hot degassing. If you want to prepare dense materials with high quality by sintering or HP, degassing should be done after milling.
For pure aluminium powder milling, the wetting agent is toluene. Since this is a volatile liquid and also stabilize the temperature in the chamber. If you have purging facility, amend with pure argon gas. This is the safe practice to handle pure aluminium.