Brass than in brass produced by cementation. These may be "natural alloys" manufactured by smelting zinc rich copper ores in redox conditions. Many have similar tin contents to contemporary bronze artefacts and it is possible that some copper-zinc alloys were accidental and perhaps not even distinguished from copper. However the large number of copper-zinc alloys now known suggests that at least some were deliberately manufactured and many have zinc contents of more than 12% wt which would have resulted in a distinctive golden color. By the 8th–7th century BC Assyrian cuneiform tablets mention the exploitation of the "copper of the mountains"
Microstructurally stable nanocrystalline alloys Microstructurally stable nanocrystalline alloys Microstructurally stable nanocrystalline alloys are alloys that are designed to resist microstructural coarsening under various thermo-mechanical loading conditions. Many applications of metal materials require that they can maintain their structure and strength despite very high temperatures. Efforts to prevent deformations from long term stress, referred to as creep, consist of manipulating alloys to reduce coarsening and migration of individual grains within the metal. The small size of individual metal grains provides high interfacial surface energy which is what prompts coarsening, the increase in grain size, and eventually metallic softening. Nanocrystalline creep is considered to follow the