Brass make brass was not recognised as a metal. The King James Bible makes many references to "brass". The Shakespearean English form of the word 'brass' can mean any bronze alloy, or copper, rather than the strict modern definition of brass. The earliest brasses may have been natural alloys made by smelting zinc-rich copper ores. By the Roman period brass was being deliberately produced from metallic copper and zinc minerals using the cementation process, and variations on this method continued until the mid-19th century. It was eventually replaced by speltering, the direct alloying of copper and zinc metal which was introduced
High entropy alloys greater than or equal to 1.1 to promote solid solution development. The atomic radii of the components must also be similar in order to form a solid solution. Zhang et al. proposed a parameter δ representing the difference in atomic radii: where r is the atomic radius of element i and formula_8. Formation of a solid solution phase requires a δ≤6.6%, but some alloys with 4%<δ≤6.6% do form intermetallics. For those alloys that do form solid solutions, an additional empirical parameter has been proposed to predict the crystal structure that will form. If the average valence electron concentration (VEC) of