Prehistoric technology Ground and polished stone tools continued to be created and used during the Neolithic period. Numeric record keeping evolved from a system of counting using small clay tokens that began in Sumer about 8000 BC. The Stone Age developed into the Bronze Age after the Neolithic Revolution. The Neolithic Revolution involved radical changes in agricultural technology which included development of agriculture, animal domestication, and the adoption of permanent settlements. The Bronze Age is characterised by metal smelting of copper and its alloy bronze, an alloy of tin and copper, to create implements and weapons. Polished stone tools continued to be
2195 aluminium alloy 2195 aluminium alloy 2195 aluminium alloy is an alloy in the wrought aluminium-copper family (2000 or 2xxx series). It is one of the most complex grades in the 2000 series, with at least 91.9% aluminium by weight. Like most other aluminium-copper alloys, 2195 is a high-strength alloy, with bad workability, and poor corrosion resistance. Being highly alloyed, it tends to fall on the higher strength and lower corrosion resistance side. As a wrought alloy, it is not used in casting. It can be welded, and is fracture resistant at cryogenic temperatures. It is one of the Weldalite family of aluminum-lithium