Metal Kristallization?

Hi everybody! I’m trying so hard to find out some about
this tecnique I heard about in Germany sometimes called
Kristallization. It’s a process used to make the metal harder. If you
want for example to make your silver or gold piece much harder that
it is normally, you need to put it in the oven for

a certain time to a certain temperature, then turn on the
temperature again or someting like that. Can anybody help me? I tryed
to look in many books

but no result.
Thank you so much to all.

Cristina - What you describe sounds to me like precipitation
hardening, when tiny amounts of a particular composition come out of
solution throughout an alloy and prevent easy deformation of the
metal. The technique would depend on exactly what alloy you have
and how it has been treated up to that point. There are huge
volumes of phase diagrams that show you how to do it for particular
alloys, but if you’re not familiar with them, I’d suggest that you
talk either to someone who knows a great deal about your alloy, or
to a metallurgist, who might be found in the materials or mechanical
engineering department of a nearby college (and who will no doubt
have access to those huge volumes).