I am not an American English native (I'm actually a German native speaker) but, when I write, I use the American style of words predominantly. However, I always use aluminium instead of aluminum, following the nomenclature that is used by all the rest of the world save for the US and Canada. It is also was the only valid IUPAC name between 1990 and 1993, since when aluminum is allowed as an acceptable variant1, but IUPAC publications strive to use the official aluminium variant.
Is it ok to break with AE and choose the BE/international version with this one word only (in a non-scientific text)?
Non-scientific means in this context any text that is not a scientific publication, among others fiction or blog posts.
1 - Connelly, Neil G.; Damhus, Ture, eds. (2005): Nomenclature of Inorganic Chemistry: IUPAC recommendations 2005, p249: Table I Names, symbols and atomic numbers of the elements (see also Section IR-3.1)
Name Symbol Atomic Number
aluminiuma Al 13
In said table's footnotes:
a: the alternative spelling aluminum is commonly used
This is not British / American language mishmash as this one just aims at one specific instance of one specific term and not a general "mix and match". This one case also is not looked at in the other question.