Short answers, pulled from the story.
The first known use of an alloy by humans was the forging of tools from meteoric iron, a naturally occurring alloy of nickel and iron that rained down from space. Ancient peoples used this rare material found in meteorites as anvils or shaped it by cold hammering into knives and arrowheads. This meteoric alloy possessed a unique Widmanstätten pattern that proved its extraterrestrial origin.
Humans began deliberately alloying copper with tin to create bronze around 2500 BC in the highlands of Anatolia. This transformation produced a material far harder and more durable than either of its components and enabled the creation of stronger weapons, tools, and armor. The scarcity of tin found mostly in Great Britain made bronze a strategic commodity that drove trade routes and conflicts across the ancient world.
Steel was generally considered an alloy primarily during the decades between 1930 and 1970 due to the work of scientists like William Chandler Roberts-Austen and Adolf Martens. Benjamin Huntsman revolutionized the industry in 1740 by melting blister steel in a crucible to even out carbon content. By 1858 Henry Bessemer developed a process of blowing hot air through liquid pig iron to reduce carbon content leading to the first large-scale manufacture of steel.
Alfred Wilm discovered precipitation hardening in 1906 when he found that an aluminum-copper-magnesium alloy increased in hardness when left to age at room temperature. This discovery known as duralumin became the primary building material for the first Zeppelins and later the airframes of modern aircraft. The Wright brothers used an aluminum alloy to construct the first airplane engine in 1903 before this breakthrough.
The Krupp Ironworks in Germany developed rust-resistant stainless steel by adding 21% chromium and 7% nickel in 1912. These modern alloys such as 304 grade stainless steel consist of complex mixtures of iron chromium and nickel designed to resist rust and corrosion while maintaining strength. The addition of these elements helped remove impurities like phosphorus sulfur and oxygen that could lead to catastrophic failure.
When steel is cooled slowly the carbon atoms have time to diffuse out of the iron and precipitate out as cementite forming a heterogeneous microstructure called pearlite that is relatively soft. However if the steel is cooled quickly a diffusionless transformation occurs trapping the carbon atoms within the iron crystals to form martensite. This process leaves the crystals very hard but much less ductile creating a material that is strong yet brittle.