Electromagnetic Testing - Eddy Current Testing Applications Chapter 5 & 6

(b) Alloying.
Dissolving any element in a solid metal causes stress in the lattice because of
the different sizes of the atoms, and so causes both hardening and a
reduction of conductivity. Alloys therefore have lower conductivity than the
pure metal they are formed from. Some impurities in metals, even in quite
small amounts, can significantly reduce the conductivity. For example, 0.1%
of phosphorus in copper reduces its conductivity from 100% IACS to 50%
IACS. This is important, because phosphorus is sometimes used to deoxidize
copper during its refining and, if so, some phosphorus remains in the material.
This material is therefore not suitable for high conductivity applications.
Charlie Chong/ Fion Zhang