more titanium and silver
Variable Load,
I did a little research on the subject and I'd like to update my response to you. From what I have read, the issue between silver and titanium alloys is more correctly a stress corrosion phenomena, and not a galvanic corrosion problem. Apparently, under certain conditions, titanium alloys will suffer stress corrosion when in contact with a more noble metal such as silver.
This only occurs with a titanium surface that is not passivated. While titanium fasteners usually have a passivated surface on the threads when new, after a few installation and removal cycles of an all metal locknut, the passivated surface of the titanium threads would be scuffed off. So one can imagine that the unpassivated titanium thread surface in intimate contact with the silver plating on the locknut would present the conditions for stress corrosion cracking to occur. The fact that the titanium studs were highly loaded (or possibly overloaded), combined with the natural stress concentrations the thread roots create, and the extreme notch sensitivity that titanium exhibits, all would contribute to a structural failure initiated by a stress corrosion crack.
Looking forward to your comments on the issue.
Regards,
riff_raff
ps. In response to ericferret's comments on silver plated shims and bushings, the (soft) silver plating is used as an anti-fretting coating, and not for corrosion prevention.