Noun
(chemistry, electronics) The brittle, bright-purple intermetallic compound AuAl2, formed when gold and aluminium are heated while in direct contact (for instance, if a gold wire is bonded to an aluminium contact pad and experiences heating due to electrical resistance).
(electronics) The problems caused by the formation of this compound, including the formation of voids in the contact area and the potential for fracture of the gold-aluminium junction.
Source: en.wiktionary.org