One of the links you provided described the cleaning a bit:
http://www.mtm-inc.com/reduce_project_risk/cleaning_aluminum_for_vacuum_applications/
But in it, it seems to refer specifically to extruded aluminum being a problem (although this does not absolve aluminum in general, even parts...
Knife edges on the edges of flanges with a maleable material gasket like copper is often used for creating UHV chamber environments.
For UHV view ports, typically say quartz or some other material, how is the UHV seal accomplished?
Is it the same mechanism? E.g. knife edges machined on...
Speaking of aluminum as UHV chamber material, the alumina layer if it is porus can be a problem as stated above, such as that of not-smooth or properly processed raw material aluminum from extrusion or casting.
But is the porus oxide layer a problem for UHV seal if you create the aluminum...