purple plague

Noun

 * 1)  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).
 * 2)  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.