are made from various elements to increase the tensile strength and hardness to improve the matters performance. The substitutional solid solutions are those in which the solute and solvent atoms are nearly the same size and the solute atoms simply substitute for solvent atoms on the crystalline lattice. The main categories of alloys are bearing alloys, corrosion resistance types, stainless steel super austenitic alloys and corrosion resistance high resistance alloys.
When a metal is alloyed with another metal either substitutional or interstitial solid solutions are formed. The substitutional solid solutions are those in which the solute and solvent atoms are nearly the same size and the solute atoms simply substitute for solvent atoms on the crystalline lattice.
Interstitial solutions made up of solids are basically the ones in which the atoms of the solute are much smaller and fit within the space between the atoms solvents which are already present on the crystalline structure.
When two different metals or alloys
are placed in intimate contact, atoms will slowly begin to migrate across the interface. These diffusion of unlike species under the influence of a chemical gradient is called chemical diffusion.Bearing alloys:Copper base alloys
offer a variety of properties for sleeve type and other types of sliding bearings. The most commonly employed copper bearing alloys are commercial bronze copper lead alloys as well as lead or unleaded alloys
or bronze. The moderate strength and hardness of pure copper are readily increased by alloying most commonly with Tin, while lead is present in cast copper base bearing alloys as a pure and discrete material.The stainless steel super austenitic alloys:
These actually represent a special class of austenitic stainless steels that contain high levels of nickel, molybdenum, and in some cases the nitrogen as well. These alloys are designed for severely corrosive environments.
They provide improved resistance to pitting and crevice corrosion. Higher nickel contents improve chloride SCC resistance while Molybdenum and nitrogen provide improved pitting and crevice corrosion resistance. These alloys are compositionally balanced to ensure fully austenitic microstructure.
The various types of alloys
are based mainly on the base metal and the manner in which these are inter mixed. They are commercial bronze, unleaded tin bronze, low lead tin bronze, medium lead tin bronze and high lead tin bronze. Amongst copper lead alloys there are similar level of inter mixing. Commercial bronze: these are lead free copper alloys which are characterised by bad anti friction characteristics but have reasonably good load carrying ability.
Unleaded tin bronze: the un-leaded copper and tin combined alloys are known as phosphor bronze because these are deoxidized carried out by phosphorus. They are used specifically in the form of cast form shaped to be utilized for specific applications. Low lead tin bronze: the inherently bad working capability in machines by tin bronzes used in cast form is improved by adding small amounts of lead.
Medium lead tin bronzes: these are cast or sintered on a steel back and used for heavy duty applications like in wrist pin bushings and heavy duty thrust surfaces. High lead tin bronzes: these contain medium to high amounts of tin and relatively high lead contents to improve anti friction characteristics.Copper lead alloys
are used extensively in automotive, aircraft and general engineering applications and as these alloys are cast or sintered to a steel backing strip from which parts are blanked and formed into full round or half round shapes specifically as per final applications.
Many materials are used as an alloying material for various uses and most of the properties are combination of the base element as well as the alloyed part. Alloy is nothing but a mix of two element and both or more of these combining elements retain their basic properties which gives an enhanced look to the overall properties of alloy.
The cobalt alloys
are considered resistant to aqueous corrosion generally fall into five categories like high carbon alloys Co-Cr-Mo, low carbon alloys
Co Cr Mo, and age hardened materials Co Ni Cr Mo, low carbon Co Mo Cr Si and high carbon Co Cr W. The resistance to corrosion of these alloys and newer cobalt alloys stems from the effects of chromium which enhances passivity in aqueous media.
- Alloys are plain mixture of various metals in ratios which appropriates the alloy in question
- Participating elements hold on to their properties and give a combined set of properties which consider the alloys characteristics
- Each individual elements carry their specific properties even in the alloy and give strength to the overall alloy property
- Alloys are considered to be good conductors of heat, and charge
- Alloys are considered for space age technologies which are essential for their specific role
- Alloys help in resisting corrosions and wear and tear
- The permanent and soft magnetic materials are made only of alloys
- All kinds of high speed steels and steels made for tools are mainly made up of alloys
- All kinds of high temperature springs and bearings are specifically made up of alloys
- Special biocompatible materials for use as orthopaedic implants or dental materials
- All kinds of machinery tools which require constant modulus and expansion are made up of specific alloys
- Alloys of aluminium when exposed to atmospheric oxygen forms a hard sealing oxide layer which is insoluble in water and also regenerates quickly when damaged
There are different types of alloys like brass, bronze as well as alloys of non-ferrous, aluminium or even magnesium.
Different Types of Alloys and Their Composition
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Al- 3% to 12%
Mn 0.03 %
The rest are magnesium
Rest are all aluminium
| Y alloy
The rest are all aluminium
Copper alloy Brass
| Yellow brass
| Admiralty brass
| Arsenical copper
The rest are copper
Cu alloy bronze
| Bell metal
| Alpha bronze
The oxide layer of aluminium alloys
like duralumin has resistive properties and although it has traces of copper, silicon and magnesium the role of aluminium is ultimate. Copper alloy like bronze has copper as the main base metal with traces of zinc, stannous and lead. Electron which is a magnesium alloy has traces of aluminium and manganese but the main element is magnesium which carries a lot of characteristics of magnesium.
Brass has the main metal as copper and zinc which has 60% of copper and the rest is zinc. This metal carries almost equal share of both metal characters. Bell metal alloy has copper as main partner of 70% and stannous of 30% which carries a lot of copper characters. Titanium alloy has components of good mechanical and chemical properties which are best used in high tensile components which has nickel and chromium as other alloy partners.