So, you think that a few ten thou of AlO2 is going to insulate the body of the chunk of Al from the 1400 F that a wood /charcoal fire generates? Also, IIRC, I quoted a figure for common alloys, many of which are eutectic. That’s one of then there SCIENCE words meaning the alloy exhibits a lower melting point than any of the constituent metals.

I guess you missed the part where I wrote that I have personally melted scrap Al alloy, to include chunks of wheels, over a wood and charcoal fire for casting. The fire was blown using a common lawn blower (sort of like a strong wind).

BTW, have you ever seen Al burn? I watched a 7200V Al power line knocked down in an ice storm bounce around until it hit a good ground in a puddle of salty water. It burned like a fuse right up to the pole transformer, which, BTW, exploded spectacularly.