The most well-known high-tin bronze bowls are those of Thailand worked on by Rajpitak, uber direction of Dr. Nigel Seeley, tiltle: The development of copper alloy metallurgy in Thailand in the pre-Buddhist period, with special reference to high-tin bronzes PhD Thesis (4 vols) University of London....Above 586oC a bronze in the beta region can be readily worked, whilst if allowed to cool the decomposition into alpha and delta phase makes it too brittle. After casting the blank in the approximate form of the desired object such as a bowl the bowl could be shaped further by hot-working around 650oC. At the end of this process the bowl could be uniformly reheated to the same temperature and then quenched to retain beta phase, hammer marks and oxide scale then removed with abrasives and then polished. Surface decoration on the bowls then cut into the surface with chisel, drill, or abrasive. Since the structure is often of alpha islands in a beta martensitic mass, signs of the working of the alloy can be seen after etching in the twinned alpha islands, suggestive of some hot-working of the bowl. There are various subtle aspects to the type of the beta quenched structures depending on tin content and quenching rate etc, bit like TTT diagrams i think were shown by or deduced by Goodway..... and in some it looks as if some retained gamma phase may occur, but this is less common.
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