I am looking for the operating temperature range both in a cold and hot environments (minimum and maximum operating temperatures) for aluminium alloy 6063.
I'm new to finding this kind of information efficiently, and I would appreciate a reference document as well.
American Society for Metals has many publications. Temperatures below ambient are no problem for any aluminum alloys. They are commonly used for natural gas separation liquefaction exchangers and piping down to −100 °C (guess at the temp.).
In the T6 condition (hardened) room temperature yield is 31000 psi; at 300 °F the short term yield is 20000 psi; 6500 psi at 400 °F, and falling fast as the temperature raises.
ASME Boiler Code will have allowable stresses which will be lower than these values. I looked in ASM Materials Handbook vol 1, 1961, it is probably not online. If this is long term, you will want creep or stress/rupture data which is not commonly available for aluminum; try in the aircraft industry.
You need to define what an "operating temperature" is, for what application.
An alloy that will work perfectly fine as a structural material for your kitchen oven will fall apart if used in aerospace applications.
Your best bet is to find alloys used in similar applications and argue, by analouge, that these alloys will also work with your application.
That said, experiment is king, and if there's any sort of safety risk, you need to investigate it before moving forward.
