The thinning of Spangold~(TM) for transmission electron microscopy studies

摘要

SpangoldTM is the name given to a family of 18 carat Au-Cu-Al alloys, in the region of 75wt% An, which are being developed for jewellery applic-ations. These alloys exploit the effect of a marten-sitic phase transformation which occurs on cooling and which induces a unique surface relief pattern to each item of jewellery. The resulting surface topography gives rise to a decorative glitter or "spangle" which is intrinsic to the alloys, and which gives them their name. In addition, as the electronic structure of the material is changed by increasing the aluminium to copper ratio, there is a shift in the reflected colours from the surface of the alloy, changing from yellow, to red, to tinges of purple, and then to white [1-3]. The spangle effect intensifies the perceived colour. Together, the spangle and the colour effects offer significant innovative opportu-nities to the designers of gold jewellery.