The following is a link to world gold Council link to two articles
by Christopher W. Corti on Metalurgy of Microalloyed 24 ct Golds
http://www.gold.org/value/sci_indu/GBull/1999_2/CORTI.PDF
http://www.gold.org/value/sci_indu/GTech/2001_33/CORTI.PDF
this is a good over view of the topic.
David