Metals - Alloying of metals

Alloying of Metals

 What is alloying and why do we use it?
Alloying is the process for mixture and composing two or more elements. Metal alloying is done for many purposes but mostly, for the radiation shielding.

We use alloying to improve certain characteristics of metals, or to give it new characteristics.

How alloying affects metals:

Alloying change the physical properties of the metal. This means that it changes such things as the strength, hardness, the ability to conduct heat and electricity, resistance to corrosion, melting point and even the colour of the metal.

Types of alloying elements.

Carbon:                                Carbon has a big affect on the properties of iron. You cannot make steel unless you add carbon to iron. Carbon is the main element that provides hardness and strength to the new alloy. On the contrary it reduces the ductility and toughness of the new alloy.

Chromium:         Chromium improves toughness and hardness and increase the resistance to corrosion. Chromium is often use to harden the new alloy and used with nickel to produce a very strong and tough metal.

 Cobalt:                Cobalt improves the strength and hardness of a metal at high temperatures.

Manganese:       Manganese also improves hardness, toughness and strength, but less than carbon does. It also decrease the ductility and toughness but less than carbon does.

Nickel:                  Nickel improves strength, toughness and resistance to corrosion.

Phosphorus:      Phosphorus increases the strength, hardness and machine-ability of the metal. However, it reduces ductility and toughness.

Copper:                Adding copper to a metal, increases its resistance to corrosion from anything that might be in the atmosphere. (chemicals or moisture) Copper can also increase the strength of a metal without reducing the ductility to much.

Tungsten:            Tungsten’s main alloying affect is in high-speed steels where it bond with carbon to form carbides that are very resistant to wear. High amounts of tungsten produce red hardness which means that the metal does not lose its hardness at high temperatures.

Boron:                  Boron can increase the hardness of the metal a lot without it losing its ductility. Boron works better if the carbon contents is low.

Titanium:            Titanium is used in combination with Boron to enhance the affect that Boron has on the metal.

Magnesium:      Magnesium is usually alloyed with aluminium. Magnesium makes the aluminium easier to shape and improves the tensile strength of the metal. It also increases the resistance to corrosion in the metal.

Tin:                        Tin makes copper much stronger and harder. However, adding the tin decrease the ability of copper to conduct heat and electricity.

Molybdenum:   Molybdenum is a very important alloying element. It is more ductile than tungsten and has a very high melting point. It can withstand extremes of temperatures without softening or expanding too much. Molybdenum is also very resistant to corrosion and can easily be welded. Most high-strength steels are made up of 0,25% to 8% molybdenum.