Andy,
I've always understod bronze fillers to have the potential to dissolve into base metals, and vice-versa. Heat control is important to avoid this phenomenon. There is a bronze solder being promoted locally for it's efficiency in the HVAC industry due to lower melting temperatures, owing to its P content, which also I understand lends to the toughness of the alloy.
Does a mechinism exist, of which I am unaware, by which P and other potential alloying elements can dissolve into other metals which are kept well below their liquid state?
Regretably, one might describe my mastery of the field of metallugy with the pronunciation "mental-allergy"- it remains rather element-airy.
Regards
d