Alloy are relatively similar in size, the atom exchange method usually happens, where some of the atoms composing the metallic crystals are substituted with atoms of the other constituent. This is called a "substitutional alloy". Examples of substitutional alloys include bronze and brass, in which some of the copper atoms are substituted with either tin or zinc atoms respectively. In the case of the interstitial mechanism, one atom is usually much smaller than the other and can not successfully substitute for the other type of atom in the crystals of the base metal. Instead, the smaller atoms become trapped in the
Antimicrobial copper-alloy touch surfaces University Hospital in Manhasset, New York. An alloy of 90% Cu 10% Ni significantly lowered the microbial burden, primarily "Staphylococci", on arm surfaces of phlebotomy chairs versus wooden arm surfaces. The median reduction for total bacteria on the copper alloy chairs arms was 90%. Use of the chair with copper arm tops resulted in a 17-fold lower risk of exposure to environmental microbes than when patients used the standard chair. The majority of the samples from the chairs with copper components were below the 500 CFU/cm level believed to represent a risk to hospital patients. The microbiocidal properties of the