Excellent electrical and thermal conductors, metals are chemical elements that form cations and ionic bonds with other elements that are not metals. Metals are highly conductive chemical elements, compounds, or alloys.
Ions of positive charge can be quickly and easily formed when electrons are stripped from metal atoms (cations). The conductivity of these ions is due to the fact that the electrons around them have been delocalized.
The resulting solid is held together by the electrostatic interactions between the ions and the cloud of electrons.
Metals such as gold, silver, platinum, mercury, uranium, aluminium, sodium, and calcium are just some of the many elements one can find in the periodic table. Alloys are also considered metals, such as brass and bronze. Metals cluster in the middle of the left side of the periodic table. Among elements in groups IA and IIA, the alkali metals are the most active.
The elements in groups IB through VIIIB are metals, and so are the transition elements. To the right of the transition metals are the primary metals. The two rows of elements directly below the main body of the periodic table are called lanthanides and actinides, respectively.
Metals are typically solid and shiny at room temperature, with mercury being the only notable exception. The melting points and densities of metals are also quite high. Many properties of metals, including their large atomic radius, low ionisation energy, and low electronegativity, can be attributed to the ease with which electrons in the valence shell of metal atoms can be removed.
Metals are distinguished by their ductility, or their ability to be bent without breaking.
The degree to which a metal can be worked with a hammer depends on its malleability. Metals that have the ductility to be drawn into wire have this property. The free movement of valence electrons within metals makes them excellent heat and electrical conductors.
The conventional model of a metal consists of a core of positively charged ions surrounded by a sea of randomly distributed electrons. Metals are concentrated on the left side of the Periodic Table of the Elements, while the non-metallic elements are located on the right.
Metals and nonmetals are separated by a diagonal line from boron (B) to polonium (Po). Metals are those elements that fall to the left of this line, and nonmetals are those that fall to the right.
The band theory can be used to gain insight into the nature of a metal as well. Metals are substances whose top energy band is only partially filled by the atoms' available electrons.
Hydrogen (74 percent), helium (24 percent), and metals (remaining elements; atomic numbers 3-118) make up 96 percent of the Sun and 24 percent of the Milky Way, respectively.
The concept of metal is meaningless in stars because the chemical bonds that give elements their properties cannot exist at stellar temperatures.
Even beyond its already high thermal conductivity, a metal's electrical conductivity benefits from its lustre, density, and ability to be deformed under stress without cleaving.
Extremely reactive and almost never found in their metallic form, alkali and alkaline earth metals are similar to many other elements in their low density, hardness, and melting temperatures.
When viewed by the naked eye, metals appear opaque, glossy, and lustrous. All else being equal, the density of metals is higher than that of nonmetals.
There is a wide range in metal densities, but lithium is the least dense solid element and osmium is the most dense. This rule is broken by the light metals, which are located in groups IA and IIA.
The high density of metals is a result of their typically compact crystal lattice structure.
Strength of metallic bonds for various metals peaks somewhere in their middle due to the fact that transition metals have an abnormally high number of delocalized electrons in the type of metallic bonds that give them their characteristic strength.
This means that most non-ferrous metals can be recycled multiple times.
The high electrical and thermal conductivity of metals can be traced back to the fact that the outer electrons of metal atoms generate a stream of virtually free electrons in the metallic link, which flow as an electron gas against the positive charge formed by the ion cores.
Though it does not take into account the precise structure of the ion lattice, the free electron model can be used to make precise mathematical predictions for the electrical conductivity, as well as the electron's contribution to the heat capacity and heat conductivity, of metals.
A metal (or other element) is combined with one or more other elements to form a solid solution known as an alloy.
Almost all metals in their purest form are either too brittle, brittle, or chemically reactive to be of practical use in most situations. The properties of individual metals can be modified by combining them into alloys.
The most widely used and economically valuable metal alloys are steel, stainless steel, cast iron, tool steel, and alloy steel.
When iron is alloyed with varying amounts of carbon, low, mid, and high carbon steels result; the more carbon present, the less ductile and tough the resulting steel is.
The alloys of aluminium, titanium, copper, and magnesium are also very useful. The electromagnetic shielding properties of magnesium are a key factor in the alloys' popularity with aerospace manufacturers; this property also makes aluminium, titanium, and magnesium desirable.
Certain alloys, such as those used in jet engines, may have more than ten different chemical components in order to meet the stringent requirements of their intended use.
The chemical reactivity of precious metals is lower than that of most elements, despite their high lustre and excellent conductivity of electricity. Gold, silver, and other precious metals were once widely used as currency backing, but today they are primarily put to use as investments and in the production of consumer goods.
Popular precious metals include gold and silver. Although other precious metals such as ruthenium, rhodium, palladium, osmium, and iridium are traded, platinum is by far the most popular.
Because of its historical and cultural significance in coinage and jewellery, silver is often mistaken for more expensive precious metals.
Table of Contents
Properties
This section focuses primarily on metal-related jargon.
Metals and their alloys have important mechanical properties that include hardness, brittleness, malleability, ductility, elasticity, toughness, density, fusibility, conductivity, and contraction and expansion that are crucial in aviation maintenance.
These terms will be used repeatedly when talking about aviation metals, so it's important that you learn their meanings now.
Hardness
A material's hardness is determined by how well it holds up under stress, such as from hammering or chiselling, or from being cut into small pieces.
For instance, steel, titanium, and aluminium alloys can be heated and worked at varying temperatures to produce varying degrees of hardness (discussed later).
Many structural components are formed from malleable metals, which are then subjected to heat treatment to harden them and retain their original shape.
A metal's durability and sturdiness depend on the type of metal it is. In this way, the grain size can be adjusted through heating or other means in a pure metal.
Heating the metal rearranges its atoms, which shrinks the grain boundaries and makes the metal malleable. However, if the metal is pounded while it is cold, a great deal of dust will be produced.
In this way, cold working strengthens the metal. It needs to be reheated before it can be used again.
It is also possible to throw off the atomic structure by inserting atoms of slightly varying sizes. Alloys like brass (a combination of copper and zinc) are stronger than the primary metals due to the atomic structure's irregularities.
Brittleness
Metals that are particularly brittle are easily damaged when subjected to even mild bending or twisting. Metals are fragile because they break or crack easily without significantly deforming. It is preferable for structural metals to not be brittle because of how often they are subjected to stress loads. Cast iron, cast aluminium, and even extremely hard steel are all brittle metals that should be handled with care.
Malleability
Metals that are malleable can be shaped into different configurations without breaking or being damaged.
Such high-quality sheet metal is required for fabricating curved parts like cowlings, fairings, and wingtips. Copper and other metals are very malleable.
Ductility
When a metal can be drawn, bent, or twisted into different shapes indefinitely without breaking, we say that it is ductile.
This characteristic is essential for metals to have when they are being used to make wire and tubing.
Ductile metals are prefered for use in aircraft because they can be easily shaped and are resilient against shock.
Aluminum alloys are used for things like cowl rings, fuselage and wing skin, and formed or extruded pieces like ribs, spars, and bulkheads. Chrome-molybdenum steel is easily malleable. Similar to malleability is the quality known as ductility.
Elasticity
Metals have elastic properties, so when the force that deforms them is removed, they spring back to their original shape.
It's preferable if a material would recover its original shape after being unloaded. When a metal is loaded beyond its elastic limit, irreversible deformation occurs.
When a metal is loaded beyond its elastic limit and the stress causes the metal to bend irreversibly, we say that the metal has been strained. No matter how much force is applied to a part of an aeroplane, its design guarantees that it will never be stressed beyond its elastic limit.
Toughness
Tough materials can be deformed in the forms of bending, stretching, and twisting without breaking, and they also resist shearing and tearing. A metal's durability against repeated impacts is crucial for its use in aviation.
Density
The density of any given substance is its mass per unit of volume. In aerospace construction, it is preferable to use the actual weight of a material per cubic inch because this figure can be used to calculate the weight of a part prior to manufacturing. Density is an important factor to consider when designing a part to ensure the aircraft's weight and balance are maintained.
Fusibility
The term "fusibility" refers to a metal's ability to melt into a liquid state when subjected to sufficient heat. To weld is to join metals by melting them together. Steel has a melting point of around 2 500 degrees Fahrenheit, while aluminium alloys melt at around 1110 degrees Fahrenheit.
Conductivity
A metal's conductivity refers to its capacity to transfer thermal energy or electrical current. The heat conductivity of a metal is crucial to the welding process because it determines the amount of heat required for successful fusion. The conductivity of the metal plays a role in determining the type of jig used to control expansion and contraction.
Radio interference can be reduced in aircraft by using bonding, but electrical conductivity is also crucial. As far as heat conduction goes, various metals have varying degrees of efficiency. Copper, for instance, has a high heat conductivity rate and is also a good electrical conductor.
Since free electrons can travel through a metal, it is possible to force them into one end and have them leave through the other. This means there are no hollow spots anywhere in the metal. Imagine a hose into which marbles can be poured, and out of which they will emerge in equal numbers. That being said, metals are conductive, meaning that electricity can travel through them. Metals are used in battery cells because of the high concentration of free electrons they contain.
There Is A Difference Between The Mechanical And Physical Properties Of An Alloy
- It is possible to quantify a thing's physical attributes. Density, melting point, conductivity, expansion coefficient, etc. are all examples of such properties.
- The metal's mechanical qualities refer to how it reacts to being subjected to stress or strain. Features like durability, pliability, and resilience to wear and tear are included.
Chemical composition and internal structure, such as grain size or crystal structure, determine the mechanical and physical properties of materials. Processing can significantly alter mechanical characteristics by rearranging the internal structure. Density and electrical conductivity may be affected by metalworking or heat treatment, but the changes are usually negligible.
When numerous alloys meet the service parameters, mechanical and physical qualities play a significant role in deciding which alloy is considered suitable for the application. Typically, engineers will design a component to have specific, measurable features.
There is often a trade-off between improved performance in one mechanical property and decreased performance in another.
Gaining, say, more strength could come at the expense of ductility. Therefore, the optimum material for the application can be chosen by having a comprehensive grasp of the product's environment.
Product designers will benefit from a discussion of some typical mechanical and physical qualities when making material selection decisions.
- Conductivity
- Corrosion Resistance
- Density
- Durability and malleability
- Toughness / Flexibility
- Fracture Toughness
- Hardness
- Plasticity
- Resistance to fatigue, shear force, tensile strength, and yield
- Toughness
- Protection from Wear
Overview of Physical Properties of Metals
It is essential to be able to differentiate between materials by their physical qualities. Physical qualities are frequently thought of as encompassing mechanical properties in the context of metallurgical research and application, however not all properties are shared. How something is tested can be used to tell physical properties apart from mechanical ones. To achieve a measurement of mechanical qualities, forces must be applied, whereas physical properties can be assessed without affecting the substance in any way.
While this is true, environmental factors certainly play a role in how some physical attributes behave. When cooled, the density of most metals actually increases because of the laws of thermal expansion and contraction. In addition, colour and appearance, which are essentially physical attributes, fluctuate based on a number of environmental conditions.
Metals have many different physical characteristics.
- Anti-corrosion properties
- Density
- Point of melting
- Statistical analysis of thermal characteristics
- Capacity for heat transfer Temperature of heat transfer
- Radiative Warming
- The ability to conduct electricity
- The presence of magnetism
Mechanical Properties of Metals
The qualities of a metal, which stand in for the metal's quality, are referred to as its "properties." Metals' mechanical characteristics can be altered through heat treatment by carefully modulating the heating and cooling rates.
The properties of a metal are reliable predictors of that metal's behaviour during both the manufacturing process and its subsequent use. The mechanical properties of metals are characterised by how the material responds to the application of a driving force (load). Contrarily, it stands for robustness in the face of assault from without.
Metals and alloys undergo heat treatment, a series of operations used in the production of machine parts to alter their mechanical properties and give them the desired operating property. Procedures may include, for instance, bringing the metal to an appropriate temperature and then allowing it to cool slowly. This is done so that the metal can acquire more favourable mechanical characteristics.
These are some of the mechanical properties of metals:
Elasticity
Metals with good elastic properties will return to their original shape when tension is released. However, there is no metal that is perfectly elastic across the board. The elastic deformation of a material under a load is called strain, and the resulting stress in the metal is what allows it to resist the load.
To calculate strain, simply divide the percentage by the number of millimetres that something has expanded or contracted from its original size.
"Stress" is defined as "load divided by cross-sectional area."
They say the steel can take a lot of pressure before breaking.
Plasticity
Permanent deformation (without fracture) as a result of external forces is referred to as plasticity in metals. The state of a metal under hot or cold temperatures determines its plasticity. Lead, for instance, has high plasticity at ambient temperatures. In contrast, cast iron lacks desirable plastic characteristics even at high temperatures.
Ductility
The ductility of a metal is its capacity to be drawn into wires or stretched without cracking. It's all about how big or small the metal crystal grains are. A metal's ductility can be quantified by the percentage of its elongation.
Extinction = Decrease in width 100/Width before enlargement
Alloys with an elongation of 15% or more are called ductile. Among all metals, gold is the most malleable.
Brittleness
The metal's brittleness characterises its ability to break without significant distortion. The brittle materials include cast iron and glass.
Hardness
The metal's hardness is its resistance to being worn down, dented, or scratched by similarly hard substances. The 10 typical materials used in the Mohs scale define the range of hardness. Using the Mohs scale, the materials are arranged from softest to hardest.
Conclusion
When combined with non-metal chemical elements, metals form cations and ionic bonds. Thanks to the electrostatic interactions between the ions and the cloud of electrons, these chemical elements, compounds, and alloys have very high conductivity. Their ability to bend without breaking, or ductility, sets them apart. They make up the majority of the left side of the Periodic Table, while the non-metallic elements occupy the right. A line drawn diagonally from boron (B) to polonium (Po) divides the metals from the nonmetals (Po).
Metals are materials in which the outermost electron shell is only partially filled. They are highly dense, glossy, dense, and resistant to cleavage when deformed. The outer electrons of metal atoms produce a stream of virtually free electrons in the metallic link, which flow as an electron gas against the positive charge formed by the ion cores, accounting for the high electrical and thermal conductivity of metals. Using the free electron model, one can make accurate mathematical predictions for a metal's electrical conductivity, as well as its heat capacity and heat conductivity, due to the electron's contribution to these quantities. Important mechanical properties include hardness, brittleness, malleability, ductility, elasticity, toughness, density, fusibility, conductivity, and contraction/expansion in metals and their alloys.
Steel, stainless steel, cast iron, tool steel, and alloy steel are the most valuable metal alloys because of their widespread use and industrial value. Platinum, for its historical and cultural significance, is the most popular precious metal, followed by gold and silver. How well something resists being hammered, chiselled, sawn into pieces, etc., is one measure of its hardness. The hardness of metal alloys can be altered by heating and working the material at different temperatures. Metal can be shaped by heating it, which rearranges its atoms and makes it malleable; however, pounding cold metal creates a lot of dust.
Metals can be made stronger through cold working, and their atomic structure can be disrupted by the introduction of atoms of slightly varying sizes. In order to create rounded components like cowlings, fairings, and wingtips, malleability is required, while ductility is necessary for producing wire and tubing. When a metal is loaded beyond its elastic limit, irreversible deformation occurs. Elasticity is the ability to recover after being unloaded. The density, melting point, conductivity, expansion coefficient, and fusibility of an alloy are discussed in detail, as are its other physical properties. Conductivity refers to the ability to transfer thermal energy or electrical current, while density measures mass per unit volume.
To be fusible means that an object can be transformed into a liquid by applying enough heat. The metal's mechanical qualities include its resistance to stress and strain, as well as its durability, malleability, and longevity. Materials' internal structure and chemical composition are what ultimately determine their mechanical and physical properties. Mechanical properties can be drastically altered during processing, but this rarely has a noticeable effect. Mechanical and physical properties are important considerations for product designers.
Among these characteristics are conductivity, corrosion resistance, density, toughness/flexibility, fracture toughness, hardness, plasticity, resistance to fatigue, shear force, tensile strength, and yield, protection from wear, and magnetism. Metals have a wide variety of physical properties, including resistance to corrosion, melting point, thermal properties, heat transfer capacity, radiative warming, and electrical conductivity. The way a metal reacts when subjected to a driving force is indicative of its mechanical properties. Elasticity, plasticity, ductility, hardness, brittleness, and extinction are just a few of these characteristics. When tension is released, an elastic material returns to its original shape, while a plastic material remains permanently deformed due to the application of force.
Hardness refers to an object's ability to withstand damage from abrasion, denting, or scratching by other, similarly hard objects. The ratio of the width before expansion to its width after extinction is 100/Width. Gold is the most malleable metal, while ductile alloys have an elongation of at least 15%.
Content Summary
- Metals cluster in the middle of the left side of the periodic table.
- The band theory can be used to gain insight into the nature of a metal as well.
- Though it does not take into account the precise structure of the ion lattice, the free electron model can be used to make precise mathematical predictions for the electrical conductivity, as well as the electron's contribution to the heat capacity and heat conductivity, of metals.
- The chemical reactivity of precious metals is lower than that of most elements, despite their high lustre and excellent conductivity of electricity.
- Popular precious metals include gold and silver.
- Metals and their alloys have important mechanical properties that include hardness, brittleness, malleability, ductility, elasticity, toughness, density, fusibility, conductivity, and contraction and expansion that are crucial in aviation maintenance.
- In this way, cold working strengthens the metal.
- Cast iron, cast aluminium, and even extremely hard steel are all brittle metals that should be handled with care.
- Copper and other metals are very malleable.
- Similar to malleability is the quality known as ductility.
- When a metal is loaded beyond its elastic limit, irreversible deformation occurs.
- Chemical composition and internal structure, such as grain size or crystal structure, determine the mechanical and physical properties of materials.
- When numerous alloys meet the service parameters, mechanical and physical qualities play a significant role in deciding which alloy is considered suitable for the application.
- Product designers will benefit from a discussion of some typical mechanical and physical qualities when making material selection decisions.
- Metals have many different physical characteristics.
- The mechanical properties of metals are characterised by how the material responds to the application of a driving force (load).
- ElasticityMetals with good elastic properties will return to their original shape when tension is released.
- The elastic deformation of a material under a load is called strain, and the resulting stress in the metal is what allows it to resist the load.
Frequently Asked Questions
Common property refers to real property that is held by two or more persons with no right of survivorship. Each has an "undivided interest" in the property and all have an equal right to use the property. It can also refer to property equally owned by all members of a group.
The structure and bonding of metals explains their properties : they are electrical conductors because their delocalised electrons carry electrical charge through the metal. they are good conductors of thermal energy because their delocalised electrons transfer energy.
Physical and mechanical properties both determine how a metal will behave in the real world. For manufacturers, understanding these properties is an important step in choosing the right materials for their products.
Malleability & Ductility – metals can bend and change shape without breaking. Conductivity – metals tend to be good conductors of heat and electricity. Luster – metals have a unique, shiny visual appearance. Magnetism – Many metals are ferromagnetic or paramagnetic.