addition for specific design and materials can often be accomplished without major reductions in the attributes associated with pure metals, like conductivity, ductility and resistance against corrosion.
If two or more metals are mixed in the liquid state to produce a final solution the resulting alloy is called a binary alloy. In case of super alloys where the utility could be within microwave cooker or baking oven as many as ten alloying elements may be used to obtain the desired performance.
The use of alloy in daily life is now irrevocable and if the good factors like high tensile strength, hardness are taken into consideration then materials like gas burners, microwave utility vessels, modern day pressure cooker, pressure valve, washing machine tub, grinder blades, and other simple daily use materials like vehicular parts of bikes and cars etc are produced.The metals nickel and copper completely dissolve into each other in liquid state and retain their complete solubility in each other on freezing to form a series of alloys.
When one type of metal is alloyed with another kind either the substitutional or interstitial solid solution are usually formed. Substituted solid based solutions are considered for those where the atoms of both solute and solvent are of nearly the same size and the solute atoms simply substitute for atoms of solvents on the crystalline lattice.
Interstitial solid solutions are those in which the solute atoms are found to be much smaller and fit with in the spaces between the existing solvent atoms on crystalline structure.
The only solute atoms small enough to fit in the interstices of metal crystals are hydrogen, nitrogen, carbon and boron.
A typical metal is hard and shiny, tough as well as strong. It helps in conducting or carries electricity and heat very well. Metals have thousands of uses in daily life and are often mixed or combined with other metals or substances to form alloys
Almost any machine or device which are used for precision instrumentation has at the least one metal in it and as the most widely used form is iron we can see the use of steel by using little amount of non-metal carbon. The use of steel is universal and the day begins with utensil made of steel. The next very common kitchen vessel is aluminium and its alloys.
The next daily use or rather universally used metal is gold which are worn by almost everyone. The ornaments made up of pure gold is never used by general public as they are found to be very soft and hence use of copper or doping with copper makes it little wearable. The doped gold is relatively strong and doesn’t bend as easily as the pure form.The door locks and door knobs are again made up of brass which are again an alloy form of zinc and copper.
High performance blades of jets or washing tub or heating elements of microwave and water heater are again nothing but doped form of the pure metals.
The common sauce pans made up of aluminium never lasts long but if doped with little magnesium, copper or silicon makes it tough enough to withstand high temperature and do not deform.
The aircraft body made up of mainly aluminium is composed of doping with copper, magnesium and manganese which makes it tough, corrosion free, light weight and is widely used in aviation industries.
An alloy is a mixture which consists of a metal and one or more other elements with various set of properties completely different from its component elements. The Examples of Alloys and their components are mentioned below:
- The use of alloys in gold based ornaments with copper is well known for ages and is mainly used for making the ornaments durable and wearable. The presence of copper makes the gold ornament strong.
- The alloy brass is used for many home decorative items and is composed of copper and zinc. These metals combined make the brass strong and durable. The door knobs and high quality locks are all made up of brass.
- The alloy of bronze is used for making statues and medals as well as home decorates. Bronze is made up of tin and copper.
- The alloys brass and bronze mentioned above are of binary forms. Duralumin is ternary as there are four metals combined.
- Stellite is an alloy made up of four elements which are used by industries to make high tensile blades and machine parts. Stellite is composed of carbon, tungsten, chromium and cobalt.
- The alloy amalgam, used for many medical activities has silver, tin, copper, and zinc with mercury, indium, and palladium.
- Steel used in all kinds of constructions and industries is an alloy of iron and carbon, while stainless steel has nickel and chromium along with iron and carbon.
- The carbon steel alloy is used for weapon making, while in household items it’s used in high tensile blade making. These are used in grinders, blenders and juicers.
Composition % of common aluminium alloys
- The cookware cutlery and other major appliances like refrigerator and gas stove, surgical instruments contain stainless steel which are mainly composed of carbon, chromium and nickel with iron as the main component.
Cast alloys:Casting of aluminium
| More than 99%
|| Metal with high ductility. Suitable for components that will be anodized
| More than 97%
|| Suitable when formability requirements are high. Used for truck bumpers and body panels
|| Moderate strength after extrusion. Used for thick materials, body components and hollow profiles. Precipitation harden able.
|| Precipitation harden able. Alloy of high strength. Used for passenger car bumpers.
is carried out as sand casting in molds of packed sand as permanent mold casting in molds of cast iron or steel and as pressure die casting in automated machines with permanent dies of tool steel.
Cast aluminium alloys have a high silicon content. It might be used for marine motor components and for flywheel castings.
Surface treatment of aluminium is essential as its passive surface layer have good corrosion resistance and a constant surface appearance.
| Desirable effect
| Improve surface appearance
Anodising or electrolytic oxidation
Anodizing and colouring lacquering
| Increase surface hardness and wear resistance
|| Hard anodizing
| Improve adherence of lacquered layers
| Decrease the electrical transition resistance as well as facilitate soldering
as a very low solubility in neutral water but the solubility increase at both low and pH values. Acid rain leaches aluminium from minerals in the soil which help in increasing aluminium concentration in streams and lakes.
The utilization of different alloys is much diversified and the most common of the metals aluminium is detailed below:
Copper nickel system
|| Field of Application
| Pure aluminium
|| Decoration strips, signs, foils, bottle caps, cans, toothpaste tubes and heat exchange lamellae
| Alloy with 1% Mn
|| Cooking utensils, kitchen equipment, roofing and facing plates
| Alloy with 2.5 – 4.5 % Mg
|| Food containers, boats
| Alloys with 1% Mg
|| Decorative anodized materials
| Cast alloys 10 % Si and 2.5 % Cu
|| Car cylinder blocks
| Alloy with 0.5 % Mg and 0.4 % Si
|| Usually alloy for extruded profiles
| Alloy with 0.7 % Mg and 0.4 % Si
|| Masts for sailing boats
| Alloy with 1.2 % Mg and 5.5 % Zn
|| Car bumpers
is used for hardening and strengthening and as most of the solid solution system are caused by distortion of the crystalline lattice of the base or solvent metal by addition of solute metal. Distortion increase with amount of the solute metal and maximum effect is found at the centre of the lattice.
Alloy use in industry is very specific and while the main use of alloy is in either aviation or marine but the ancillary divisions are also involved in large scale use of alloys.
The aircraft industry use duralumin which is a main alloy of aluminium, the marine engineering uses aluminium with silicon doping materials while other ancillary industries uses stainless steel for all kinds of specific items. The medical industries uses stainless equipment’s as these are corrosion free and can be disinfected easily.