You have some cheap pure aluminium.
To machine it keep it wet with suds, paraffin or WD40, 20-30° rake on the tool and slow revs.
Alternatively, bin and buy some 6082 or 6063 grade. Always check that the material is what you asked for as it is impossible to tell a grade of aluminium by looking at it. Been caught out a few times in the past.
Trev