Alloy is a substance with metallic characteristics synthesized by a certain method from two or more metals and metals or non-metals. It is generally obtained by melting into a homogeneous liquid and solidifying. According to the number of constituent elements, it can be divided into binary alloys, ternary alloys and multi-element alloys.
The production of alloys by mankind began with the production of bronzes. The Babylonians were the first to produce alloys in the world. The Babylonians began to refine bronze (alloy of copper and tin) 6000 years ago. China is also one of the earliest countries in the world to research and produce alloys. In the Shang Dynasty (more than 3000 years ago), the bronze (copper-tin alloy) process was very developed; about the 6th century BC (late Spring and Autumn period), it was forged (remaining Heat-treated) a sharp sword.
Alloys are macroscopically uniform, diversified substances containing metal elements, and generally have metal characteristics. Any element can be used as alloying elements, but a large amount of added is still metal. The most basic and independent substances that make up an alloy are called components, or Abbreviated as yuan. An alloy composed of two components is called a binary alloy, an alloy composed of three components is called a ternary alloy, and an alloy composed of more than three components is called a multi-element alloy. In the solid state, an alloy It may be a single phase or a mixture of multiple phases; it may be crystalline, quasicrystalline or amorphous. The difference in crystalline alloys depends on the atomic radius, electronegativity, and electron concentration of its constituent elements. The possible phases are solid solutions that maintain the same structure as the pure element of the substrate and inter-mediate phases that do not have the same structure as any constituent elements. Intermediate phases include normal valence compounds, electronic compounds, laves phases, σ phases, interstitial phases and interstitial compounds with complex structures, etc. The possible phases of the alloy in the equilibrium state can be known from the phase equilibrium diagram.
The structure and properties of the constituent phases in the alloy play a decisive role in the performance of the alloy. At the same time, the changes in the alloy structure, namely the relative number of phases in the alloy, the changes in the grain size, shape and distribution of each phase, also affect the performance of the alloy. Great influence. Therefore, the combination of various elements to form a variety of different alloy phases, and then through appropriate treatment may meet a variety of different performance requirements.
The term alloy is now also used in polymer chemistry, which refers to a composite material made by blending a polymer or copolymer with another polymer or elastomer under certain conditions, such as styrene-acrylonitrile copolymer resin Blended with butadiene-acrylonitrile rubber.