This presentation introduces the basic metallurgy of jewelry metals (gold, silver, platinum and palladium) to individuals involved in the design and manufacture of jewelry. It picks up on the Mark Grimwade series presented in past years at this Symposium and gives an understanding of how properties of jewelry metals and alloys can be manipulated by alloying additions and mechanical and thermal treatments. The variation of properties with alloy composition are shown in the context of the influence of alloying additions and the microstructure. The basis for this is explained in simple mechanistic terms. The effect of working and heat treatment on mechanical properties and the recovery of ductility by annealing are also explained in terms of changes to the microstructure-how these can be influenced is also shown. The influence of minor alloying additions and impurities on structure and properties is discussed in terms of grain size control and embrittlement. The importance of phase diagrams as "road maps" to predicting microstructure and properties is explained, and how they can limit important properties such as workability is discussed.

Author: Dr. Christopher W. Corti