Editing Beryllium copper (section)

== Specialized variants ==
''High-strength beryllium copper'' alloys contain as much as 2.7% beryllium (cast), or 1.6-2% beryllium with about 0.3% [[cobalt]] (wrought). The strength is achieved by age hardening. The thermal conductivity of these alloys lies between that of steel and aluminum. The cast alloys are frequently formed with injection molds. The wrought alloys are designated by [[unified numbering system|UNS]] as C17200 to C17400, the cast alloys are C82000 to C82800. The hardening process requires rapid cooling of the annealed metal, resulting in a solid-state solution of beryllium in copper, which is then kept at 200-460&nbsp;°C for at least an hour, producing a precipitation of metastable [[beryllide]] crystals in the copper matrix. Over-aging beyond the equilibrium phase depletes the beryllide crystals and reduces their strength. The beryllides in cast alloys are similar to those in wrought alloys.

''High conductivity beryllium copper'' alloys contain as much as 0.7% beryllium with some nickel and cobalt. The thermal conductivity of these alloys is greater than that of aluminum and slightly less than that of pure copper; they are often used as electrical contacts.<ref>{{cite web |url=http://www.mmsonline.com/articles/edming-beryllium-copper-an-introduction |title=Feature&nbsp;-- EDMing Beryllium Copper: An Introduction |publisher=Mmsonline.com |accessdate=2010-10-17 |url-status=live |archiveurl=https://web.archive.org/web/20110614091228/http://www.mmsonline.com/articles/edming-beryllium-copper-an-introduction |archivedate=2011-06-14 }}</ref>