High-tin bronze bowl making in Kerala, South India, and its archaeological implications
Publication Type:Book Chapter
Source:South Asian Archaeology 1993: Proceedings of the Twelfth International Conference of the European Association of South Asian Archaeologists held in Helsinki University 5-9 July 1993, SuomalainenTiedeakatemia, Volume II, Helsinki, p.675–705 (1994)
High-tin beta bronzes are an unusual group of binary copper-tin alloys of 20-25% tin which have special properties skilfully exploited in different contexts in Asian antiquity to make bowls, gongs, coins and bracelets. Although the alloy is quite brittle with limited workability, it can be annealed and worked to a considerable extent in the temperature range of 586-775 C due to the formation of a super-plastic martensitic beta phase. This beta phase is meta-stable and may be retained only by quenching in the above temperature range, but its retention leads to improved tensile strength and reduces the brittleness of the alloy. The alloy also has musical properties and is bright golden when polished.