Alloy was used by the Inuit people. Native copper, however, was found worldwide, along with silver, gold, and platinum, which were also used to make tools, jewelry, and other objects since Neolithic times. Copper was the hardest of these metals, and the most widely distributed. It became one of the most important metals to the ancients. Eventually, humans learned to smelt metals such as copper and tin from ore, and, around 2500 BC, began alloying the two metals to form bronze, which was much harder than its ingredients. Tin was rare, however, being found mostly in Great Britain. In the Middle
2519 aluminium alloy 2519 aluminium alloy AA 2519 is an aluminium alloy principally containing copper (5.3–6.4%) as an alloying element. It also contains 0.25% silicon, 0.30% iron, 0.10–0.50% manganese, 0.05–0.40% magnesium, 0.10% zinc, 0.02–0.10% titanium, 0.05–0.15% vanadium, 0.10–0.25% zirconium, 0.40% silicon-iron compounds, and up to 0.15% trace elements. The density of 2519 aluminium is . It was first registered in 1985, in the United States. One application for this alloy is in aircraft armor, where it has equivalent ballistic characteristics to AA 7039, and a reduced susceptibility to stress corrosion cracking as compared to AA 5083. AA 2519-T87 plate is weldable using AA