At what temperature did melting begin?

Each metal and their alloys have different properties. One of these properties is the melting point. Each metal melts at a different temperature. All that is needed to transfer a substance from a solid to a liquid state is a heat source that will heat the metal to a certain temperature.

Since each metal has a different melting point, it is possible to determine which metal is less resistant to temperature or more. So the most fusible metal is mercury , it is ready to go into a liquid state at a temperature of 39 degrees Celsius . But tungsten (which is what tungsten electrodes for argon welding are actually made of) will melt only when the temperature reaches 3422 degrees Celsius .

For alloys such as steel and others, it is quite difficult to determine the temperature at which they will melt. The whole complexity is in their composition... Since the composition is different, the melting point is different. Typically, alloys are given a temperature range at which they will melt. In general, the melting point of metals is an interesting topic.

What is melting point

Each metal has unique properties, and this list includes its melting point. When melting, the metal changes from one state to another, namely, from solid to liquid. To fuse a metal, you need to bring heat closer to it and heat it to the required temperature - this process is called the melting point. At the moment when the temperature reaches the desired level, it can still remain in a solid state. If you continue the impact, the metal or alloy will begin to melt.

Melting and boiling are not the same thing. The point at which a substance transitions from solid to liquid is often referred to as the melting point of the metal. In the molten state, the molecules do not have a specific arrangement, but attraction holds them close together; in liquid form, the crystalline body leaves volume, but the shape is lost.

During boiling, the volume is lost, the molecules interact very weakly with each other, move chaotically in different directions, and separate from the surface. Boiling point is the process by which the pressure of metal vapor is equal to the pressure of the external environment.

In order to simplify the difference between critical heating points, we have prepared a simple table for you:

Property	Melting temperature	Boiling temperature
Physical state	The alloy transforms into a melt, the crystalline structure is destroyed, and granularity passes through	Transforms into a gas state, some molecules can fly away outside the melt
Phase transition	Equilibrium between solid and liquid	Pressure equilibrium between metal vapor and air
Influence of external pressure	No changes	There are changes, the temperature decreases with discharge

Melting point prediction (Lindemann criterion)

An attempt to predict the melting point of crystalline materials was made in 1910 by Frederick Lindemann [6]. The idea was the observation that the average amplitude of thermal fluctuations increases with increasing temperature. Melting begins when the vibration amplitude becomes large enough for neighboring atoms to partially occupy the same space.

The Lindeman criterion states that melting is expected when the rms value of the oscillation amplitude exceeds a threshold value.

The melting point of crystals is described quite well by the Lindemann formula [7]:

Tλ=xm29ℏ2MkBθrs2{displaystyle T_{lambda }={frac {x_{m}^{2}}{9hbar ^{2}}}Mk_{B}theta r_{s}^{2}}

where rs{displaystyle r_{s}} is the average radius of the unit cell, θ{displaystyle theta } is the Debye temperature, and the parameter xm{displaystyle x_{m}} for most materials varies in the range of 0.15-0.3.

Melting point - calculation

Lindemann's formula served as a theoretical basis for melting for almost a hundred years, but was not developed due to low accuracy.

Test Aggregate states of matter. Melting and solidification of crystalline bodies, grade 8

Test Aggregate states of matter. Melting and solidification of crystalline solids grade 8 with answers. The test includes 18 tasks.

1. The state of aggregation of a substance is its presence in the form

1) a solid body 2) a liquid body 3) a gaseous body 4) any of these three bodies

2. In what state of aggregation can iron and mercury exist?

1) iron in a solid, mercury in a liquid 2) both iron and mercury in a liquid 3) both iron and mercury in a solid 2) both substances can be in any state of aggregation

3. What determines what specific state of aggregation a substance is in?

Graphical representation of melting and solidification processes

A graph of the melting and solidification of crystalline solids provides a visual representation of the time dependence of these phase transitions.

Rice. 2. Water-ice melting and solidification graph.

Ordinary water is a good example to illustrate the phenomena discussed. In the presented graph, time t is plotted along the abscissa axis, and temperature is plotted along the ordinate axis. Let initially, at the moment of time t = 0, when the temperature of the ice (crystal) was equal to -400C, the heat supply - heating - will begin. Let us next consider the time dependence of the temperature dependence T(t):

In section AB, from -400C to 00C (melting temperature of ice), ice exists in crystalline form;
Section BC - the melting stage occurs, both ice and water are present. The temperature remains constant, equal to 00C;
CD - at point C melting has ended, there is only a liquid phase - water;
DE - at point D heating has stopped, cooling occurs up to point E, i.e. up to a temperature of 00C. Only liquid water is present;
EF - at point E, solidification begins, ice crystals appear, but at the same time there is also a liquid phase. The temperature remains constant, equal to 00C;
FK - at point F complete solidification has occurred, only ice remains in crystalline form, the temperature of which gradually decreases.

At what temperature does it melt?

Metal elements, whatever they are, melt almost one to one. This process occurs when heated. It can be both external and internal. The first takes place in a furnace, and for the second, resistive heating is used, passing electricity or induction heating. The impact is almost the same. When heated, the amplitude of molecular vibrations increases. Structural lattice defects are formed, which are accompanied by the breaking of interatomic bonds. The process of lattice destruction and the accumulation of such defects means melting.

Different substances have different melting points. Theoretically, metals are divided into:

Low-melting - temperatures up to 600 degrees Celsius are sufficient to obtain a liquid substance.
Medium melting - requires a temperature of 600 to 1600 ⁰C.
Refractory are metals that require temperatures above 1600 ⁰C to melt.

Melting iron

The melting point of iron is quite high. A technically pure element requires a temperature of +1539 °C. This substance contains an impurity - sulfur, and it can only be extracted in liquid form.

Without impurities, pure material can be obtained by electrolysis of metal salts.

Melting cast iron

Cast iron is the best metal for smelting. The high fluidity rate and low shrinkage rate make it possible to use it more effectively during casting. Next, consider the boiling point of cast iron in degrees Celsius:

Gray – the temperature can reach 1260 degrees. When pouring into molds, the temperature can rise to 1400.
White – the temperature reaches 1350 degrees. It is poured into molds at 1450.

Important! The melting rates of a metal such as cast iron are 400 degrees lower compared to steel. This significantly reduces energy costs during processing.

Melting steel

Melting steel at a temperature of 1400 °C

Steel is an alloy of iron mixed with carbon. Its main benefit is strength, since this substance is capable of maintaining its volume and shape for a long time. This is due to the fact that the particles are in an equilibrium position. Thus, the forces of attraction and repulsion between particles are equal.

Reference! Steel melts at 1400 degrees Celsius.

Melting aluminum and copper

The melting point of aluminum is 660 degrees, which means that it can be melted at home.

Pure copper is 1083 degrees, and for copper alloys it ranges from 930 to 1140 degrees.

Metal melting process

This process refers to the transition of a substance from a solid to a liquid state.
When the melting point is reached, the metal can be in either a solid or liquid state; further increase will lead to the complete transition of the material into a liquid. The same thing happens during solidification - when the melting point is reached, the substance will begin to transition from a liquid to a solid state, and the temperature will not change until complete crystallization.

It should be remembered that this rule applies only to pure metal. Alloys do not have a clear temperature boundary and undergo state transitions in a certain range:

Solidus is the temperature line at which the most fusible component of the alloy begins to melt.
Liquidus is the final melting point of all components, below which the first alloy crystals begin to appear.

It is impossible to accurately measure the melting point of such substances; the point of transition of states is indicated by a numerical interval.

Depending on the temperature at which metals begin to melt, they are usually divided into:

Low-melting, up to 600 °C. These include tin, zinc, lead and others.
Medium melting, up to 1600 °C. Most common alloys, and metals such as gold, silver, copper, iron, aluminum.
Refractory, over 1600 °C. Titanium, molybdenum, tungsten, chromium.

There is also a boiling point - the point at which the molten metal begins to transition into a gaseous state. This is a very high temperature, typically 2 times the melting point.

Effect of pressure

The melting temperature and the equal solidification temperature depend on pressure, increasing with its increase.
This is due to the fact that with increasing pressure the atoms come closer to each other, and in order to destroy the crystal lattice they need to be moved away. At increased pressure, greater thermal energy is required and the corresponding melting temperature increases. There are exceptions when the temperature required to transform into a liquid state decreases with increased pressure. Such substances include ice, bismuth, germanium and antimony.

Metal crystal lattices

In its ideal form, it is generally accepted that metals have a cubic lattice (real substances may have flaws). There are equal distances between molecules horizontally and vertically.

A solid substance is characterized by constancy:

shapes, the object retains linear dimensions in different conditions;
volume, the object does not change the amount of substance it occupies;
mass, the amount of a substance expressed in grams (kilograms, tons);
density, unit volume contains constant mass.

When transitioning into a liquid state, having reached a certain temperature, the crystal lattices are destroyed. Now we can’t talk about constancy of form. The liquid will take the form in which it is poured.

When evaporation occurs, only the mass of the substance remains constant. Gas will take up the entire volume that will be provided to it. Here we cannot say that density is a constant value.

When liquids combine, the following options are possible:

Liquids completely dissolve in one another, as do water and alcohol. The concentration of substances will be the same throughout the entire volume.
Liquids are stratified by density, the connection occurs only at the interface. It is only temporarily possible to obtain a mechanical mixture. Mix liquids with different properties. An example is oil and water.

Metals form alloys in the liquid state. To obtain an alloy, each of the components must be in a liquid state. With alloys, phenomena of complete dissolution of one in another are possible. Options cannot be excluded when the alloy will be obtained only as a result of intensive mixing. In this case, the quality of the alloy is not guaranteed, so they try not to mix components that do not allow obtaining stable alloys.

The resulting substances, soluble in each other, when solidified, form crystal lattices of a new type. Define:

Heliocentered crystal lattices are also called body-centered. In the middle there is a molecule of one substance, and four more molecules of another are located around it. It is customary to call such lattices loose, since the bonds between metal molecules in them are weaker.
Face-centered crystal lattices form compounds in which the component molecules are located on the faces. Metallurgists call such crystalline alloys dense. In reality, the density of the alloy can be higher than that of each of the components included in the composition (alchemists of the Middle Ages were looking for options for alloys in which the density would correspond to the density of gold).

Strength of metals

In addition to the ability to transition from a solid to a liquid state, one of the important properties of a material is its strength - the ability of a solid body to resist destruction and irreversible changes in shape. The main indicator of strength is the resistance that occurs when a pre-annealed workpiece breaks. The concept of strength does not apply to mercury because it is in a liquid state. The designation of strength is accepted in MPa - Mega Pascals.

There are the following strength groups of metals:

Fragile. Their resistance does not exceed 50MPa. These include tin, lead, soft-alkaline metals
Durable, 50−500 MPa. Copper, aluminum, iron, titanium. Materials of this group are the basis of many structural alloys.
High strength, over 500 MPa. For example, molybdenum and tungsten.

Determination of specific heat of fusion

The specific heat of fusion (designated by the Greek letter “lambda” - λ) is a physical quantity equal to the amount of heat (in joules) that must be transferred to a solid body weighing 1 kg in order to completely transform it into the liquid phase. The formula for the specific heat of fusion looks like this:

$$ λ ={Q over m}$$

Where:

m is the mass of the melting substance;

Q is the amount of heat transferred to the substance during melting.

Values for different substances are determined experimentally.

Knowing λ, we can calculate the amount of heat that must be imparted to a body of mass m for its complete melting:

$$Q={λ*m}$$

What does melting temperature depend on?

For different substances, the temperature at which the structure is completely reconstructed to the liquid state is different. If we take into account metals and alloys, then it is worth noting the following points:

Metals are not often found in their pure form. The temperature directly depends on its composition. As an example, we will indicate tin, to which other substances (for example, silver) can be added. Impurities make the material more or less resistant to heat.
There are alloys that, due to their chemical composition, can transform into a liquid state at temperatures above one hundred and fifty degrees. There are also alloys that can “hold” when heated to three thousand degrees and above. Taking into account the fact that when the crystal lattice changes, the physical and mechanical qualities change, and operating conditions can be determined by the heating temperature. It is worth noting that the melting point of a metal is an important property of a substance. An example of this is aviation equipment.

Heat treatment, in most cases, almost does not change the resistance to heat. The only sure way to increase resistance to heat is to make changes to the chemical composition; this is why steel is alloyed.

Crystallization

When the temperature of a liquid decreases, its molecules become less mobile. And the attractive forces that hold molecules in a certain strict order, characteristic of a solid, increase.

If a liquid substance is cooled to a certain temperature, it will solidify. The process of phase transition from liquid to solid is called crystallization

. Unlike melting, when a substance receives heat, during crystallization it releases it, and its temperature decreases.

The temperature at which this process occurs is called the crystallization temperature

. For a pure substance, the melting point is equal to the crystallization temperature.

Like melting, crystallization also occurs gradually. Likewise, a liquid and a solid will have the same temperature until the entire substance solidifies.

Liquid tin melted by a soldering iron solidifies and becomes solid when we remove the soldering iron. Molten liquid metal poured into molds solidifies as the temperature drops.

We observe crystallization in nature every year, when water in reservoirs freezes at low temperatures and snowflakes fall to the ground instead of raindrops.

Why does a solid become liquid?

Heating a solid body leads to an increase in the kinetic energy of atoms and molecules, which at normal temperatures are located clearly at the nodes of the crystal lattice, which allows the body to maintain a constant shape and size. When certain critical speed values are reached, atoms and molecules begin to leave their places, bonds are broken, the body begins to lose its shape - it becomes liquid. The melting process does not occur abruptly, but gradually, so that for some time the solid and liquid components (phases) are in equilibrium. Melting refers to endothermic processes, that is, those that occur with the absorption of heat. The opposite process, when a liquid solidifies, is called crystallization.

Rice. 1. Transition of the solid, crystalline state of a substance into the liquid phase.

It was discovered that until the end of the melting process the temperature does not change, although heat is constantly supplied. There is no contradiction here, since the incoming energy during this period of time is spent on breaking the crystalline bonds of the lattice. After the destruction of all bonds, the influx of heat will increase the kinetic energy of the molecules, and consequently, the temperature will begin to rise.

Rice. 2. Graph of body temperature versus heating time.

Melting

melting of propane, melting of lead Melting
is the process of transition of a body from a crystalline solid state to a liquid, that is, the transition of a substance from one state of aggregation to another.

Melting occurs with the absorption of specific heat of fusion

and is a first-order phase transition, which is accompanied by an abrupt change in heat capacity at a specific temperature point of transformation for each substance - the melting point.

The ability to melt refers to the physical properties of a substance

At normal pressure, the highest melting point

among metals it has tungsten (3422 °C), among simple substances - carbon (according to various sources, 3500 - 4500 °C) and among arbitrary substances - tantalum-hafnium carbide Ta4HfC5 (3942 °C). We can assume that helium has the lowest melting point: at normal pressure it remains liquid at arbitrarily low temperatures.

Many substances at normal pressure do not have a liquid phase. When heated, they immediately transform into a gaseous state by sublimation.

1 Melting of mixtures and solid solutions
2 Melting kinetics 2.1 Nature of melting
2.2 Melting dynamics
2.3 Melting in two-dimensional systems

3 See also

4 Notes

5 Links

Melting mixtures and solid solutions

Alloys generally do not have a specific melting point; the process of their melting occurs in a finite temperature range. In the temperature-relative concentration diagrams, there is a finite region of coexistence of the liquid and solid states, limited by the liquidus and solidus curves. A similar situation occurs in the case of many solid solutions.

Amorphous bodies also do not have a fixed melting temperature; they turn into a liquid state gradually, softening as the temperature rises.

Melting kinetics

Technically, the melting of a substance is carried out by supplying thermal energy from outside the sample (external heating, for example, in a thermal furnace) or directly throughout its entire volume (internal heating, for example, resistive heating when passing current through the sample, or induction heating in a high-frequency electromagnetic field ). The melting method does not affect the main characteristics of the process - temperature and latent heat of fusion, but determines the external picture of melting, for example, the appearance of a quasi-liquid layer on the surface of the sample during external heating.

It is believed that melting is characterized by the loss of long-range orientational interatomic order in the crystal with a transition to “liquid-like” or “gas-tight” disorder.

Nature of melting

Let us first explain why, at a certain temperature, a body prefers to break some of the interatomic bonds and go from an ordered state (crystal) to a disordered state (liquid).

As is known from thermodynamics, at a fixed temperature a body tends to minimize free energy. At low temperatures, the second term (the product of temperature and entropy) is insignificant, and as a result, everything comes down to minimizing ordinary energy.

In this case, ordinary energy will increase slightly, but entropy will also increase greatly, which will result in a decrease in free energy.

Melting dynamics

In dynamics, melting occurs as follows. As the temperature of a body increases, the amplitude of thermal vibrations of its molecules increases, and from time to time structural defects of the lattice appear in the form of atomic jumps, the growth of dislocations and other disturbances of the crystal lattice.

Each such defect, the emergence and movement of dislocations, requires a certain amount of energy, since it is accompanied by the rupture of some interatomic bonds. The stage of birth and accumulation of defects is called the premelting stage. In addition, at this stage, as a rule, with external heating, a quasi-liquid layer appears on the surface of the body.

It is believed that at a certain temperature the concentration of defects becomes so large that it leads to a loss of orientational order in the sample.

Temperature fluctuations of atoms in the crystal lattice Behavior of the liquid after the crystal passes through the melting point, as, on average, constant breaks and restorations of intercluster and intracluster interatomic bonds for a given temperature (short thickened segments - broken bonds)

Due to the fact that the mechanism of thermal destruction of a crystal due to the formation of defects and the growth of dislocations, which occurs over a wide temperature range, does not lead to a phase transformation of the 1st kind, that is, to a jump in the thermodynamic characteristics of a substance at a specific temperature point for each substance, Lindeman developed simple ideas about the course of the melting process, according to which the amplitude of vibration of particles at the melting point increases so much that it becomes comparable to the interatomic distance in the crystal lattice and leads to destruction of the lattice and loss of orientational interatomic order. In fact, this “melting factor” is the basis of most models with the determining role of the repulsive part of the pair interaction potential and the imposition of conditions for the transition from order to “liquid-like” or “gas-tight” disorder, calculated by Monte Carlo and molecular dynamics methods. However, it was found that at the melting point the root mean square displacement of atoms from equilibrium is only about 1/8 of the interatomic distance, which excludes the Lindemann model, that is, the collision of atoms, as a “melting factor”. In this case, the energy of the atoms is significantly lower than the potential energy of atomization of the crystal lattice.

Further studies showed that the dynamics of melting of a crystalline body, as a phase transformation of the 1st kind, is determined (in contrast to the model of accumulation of defects and dislocations) by a “catastrophic” (crash) conformational transformation of the structure of a group of atoms, accompanied by the destruction of interatomic bonds when overcoming a potential barrier with the expenditure of a constant amount of energy, lower than the lattice atomization energy, and equal to the specific heat of fusion.

This mechanism leads to an experimentally confirmed cluster structure of a bound (condensed) liquid state with a constant (for a given temperature) average number of breaking and reforming intercluster and intracluster interatomic bonds, which determines the mobility (fluidity) of the liquid.

With increasing temperature, the number of atoms in clusters decreases and at the boiling point the substance passes into a monoatomic (monomolecular) gaseous state.

Melting in two-dimensional systems

In two-dimensional or quasi-two-dimensional systems, the crystal is a much more shaky object than in the three-dimensional case, namely, a two-dimensional crystal has no long-range positional order. For comparison, in the one-dimensional case, a crystal at a finite temperature cannot be stable at all.

As it turned out, this leads to the melting of a two-dimensional crystal occurring in two stages. First, the crystal goes into the so-called hexatic phase, in which the short-range positional order is lost, but the orientational order is preserved, and then the orientational order is also lost and the body becomes liquid.

Notes

↑
S. T. Zhukov Chemistry 8-9 grades, Chapter 1. Basic ideas and concepts of chemistry
↑
The scatter of experimental data is apparently associated with the graphite-carbyne phase transition and different heating rates during measurements. Klimovsky I. I., Markovets V. V.
The influence of the graphite-carbyne phase transition on the emissivity of graphite samples when heated to temperatures of 3000 K or more // International Scientific Journal for Alternative Energy and Ecology. - 2007. - No. 6 (50). — P. 50-59.
↑
Meyer K. Physico-chemical crystallography, M.
, "Metallography", 1972
↑
LindemannF.A. // Phys.Z., 1910, v.11, p.609
↑
Wood WW, Jacobson JD Preliminary Results from a Recalculation of the Monte Carlo Equation of State of Hard Spheres // J. Chem. Phys.. - 1957. - No. 27. - P. 1207. - DOI:10.1063/1.1743956.
↑
Alder BJ
, Wainwright TE Phase Transition in Elastic Disks // Phys. Rev.. - 1962. - No. 127. - P. 359. - DOI:10.1103/PhysRev.127.359.
↑
Hoover WG, Gray SG, Johnson KW Thermodynamic Properties of the Fluid and Solid Phases for Inverse Power Potentials // J. Chem. Phys.. - 1971. - No. 55. - P. 1128. - DOI:10.1063/1.
1676196.
↑
Pines D. Elementary excitations in solids. M., Mir, 1965.

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Melting point table

To find out what temperature is needed to melt metals, a table of increasing temperature indicators will help.

Element or connection	Required temperature conditions
Lithium	+18°С
Potassium	+63.6°С
Indium	+156.6°С
Tin	+232°С
Thallium	+304°С
Cadmium	+321°С
Lead	+327°С
Zinc	+420°С

Melting table for medium-melting metals and alloys.

Element or alloy	Temperature
Magnesium	+650°С
Aluminum	+660°С
Barium	+727°С
Silver	+960°С
Gold	+1063°С
Manganese	+1246°С
Copper	+1083°С
Nickel	+1455°С
Cobalt	+1495°С
Iron	+1539°С
Durali	+650°С
Brass	+950…1050°С
Cast iron	+1100…1300°С
Carbon steels	+1300…1500°С
Nichrome	+1400°С

Melting table for refractory metals and alloys.

Item name	Temperature
Titanium	+1680°С
Platinum	+1769.3°С
Chromium	+1907°С
Zirconium	+1855°С
Vanadium	+1910°С
Iridium	+2447°С
Molybdenum	+2623°С
Tantalum	+3017°С
Tungsten	+3420°С

Classification of metals by melting point

In physics, the transition of a solid into a liquid state is characteristic only of substances with a crystalline structure. The melting point of metals is often indicated by a range of values; for alloys, it is difficult to accurately determine heating to the boundary phase state. For pure elements, every degree matters, especially if these are fusible elements,

doesn't matter. The summary table of t indicators is usually divided into 3 groups. In addition to low-melting elements, which heat up to a maximum of +600°C, there are refractory elements that can withstand heating above +1600°C, and medium-melting ones. This group includes alloys that form a melt pool at temperatures from +600 to 1600°C.

Low-melting metals

Low-melting metals have a melting point below 600°C. These are zinc, tin, bismuth. Such metals can be melted at home by heating them on the stove, or using a soldering iron. Low-melting metals are used in electronics and technology to connect metal elements and wires for the movement of electric current. The melting point of tin is 232 degrees, and zinc is 419.

Table of low-melting metals and alloys (up to 600C o)

Item name	Latin designation	Temperatures
Item name	Latin designation	Melting	Boiling
Tin	Sn	232 Co	2600 So
Lead	Pb	327 Co	1750 So
Zinc	Zn	420 Co	907 Co
Potassium	K	63.6 Co	759 Co
Sodium	Na	97.8 Co	883 Co
Mercury	Hg	— 38.9 Co	356.73 Co
Cesium	Cs	28.4 Co	667.5 Co
Bismuth	Bi	271.4 Co	1564 Co
Palladium	Pd	327.5 Co	1749 Co
Polonium	Po	254 Co	962 Co
Cadmium	Cd	321.07 Co	767 Co
Rubidium	Rb	39.3 Co	688 Co
Gallium	Ga	29.76 So	2204 Co
Indium	In	156.6 Co	2072 Co
Thallium	Tl	304 Co	1473 Co
Lithium	Li	18.05 So	1342 Co

Medium melting metals

Medium-melting metals begin to transform from solid to liquid at temperatures from 600°C to 1600°C. They are used to make slabs, reinforcements, blocks and other metal structures suitable for construction. This group of metals includes iron, copper, aluminum, and they are also part of many alloys. Copper is added to alloys of precious metals such as gold, silver, and platinum. 750 gold consists of 25% alloy metals, including copper, which gives it a reddish tint. The melting point of this material is 1084 °C. And aluminum begins to melt at a relatively low temperature of 660 degrees Celsius. This is a lightweight, ductile and inexpensive metal that does not oxidize or rust, therefore it is widely used in the manufacture of tableware. The melting point of iron is 1539 degrees. This is one of the most popular and affordable metals, its use is widespread in the construction and automotive industries. But due to the fact that iron is subject to corrosion, it must be additionally processed and covered with a protective layer of paint, drying oil, or prevent moisture from entering.

Table of medium-melting metals and alloys (from 600C to 1600C)

Item name	Latin designation	Temperature
Item name	Latin designation	Melting	Boiling
Aluminum	Al	660 Co	2519 So
Germanium	Ge	937 Co	2830 Co
Magnesium	Mg	650 Co	1100 So
Silver	Ag	960 Co	2180 Co
Gold	Au	1063 Co	2660 Co
Copper	Cu	1083 Co	2580 Co
Iron	Fe	1539 So	2900 So
Silicon	Si	1415 Co	2350 Co
Nickel	Ni	1455 Co	2913 Co
Barium	Ba	727 Co	1897 Co
Beryllium	Be	1287 Co	2471 Co
Neptunium	Np	644 Co	3901.85 Co
Protactinium	Pa	1572 Co	4027 Co
Plutonium	Pu	640 Co	3228 Co
Actinium	Ac	1051 Co	3198 Co
Calcium	Ca	842 Co	1484 Co
Radium	Ra	700 Co	1736.85 So
Cobalt	Co	1495 Co	2927 Co
Antimony	Sb	630.63 Co	1587 Co
Strontium	Sr	777 Co	1382 Co
Uranus	U	1135 Co	4131 Co
Manganese	Mn	1246 Co	2061 Co
Konstantin	1260 So
Duralumin	Alloy of aluminum, magnesium, copper and manganese	650 Co
Invar	Nickel iron alloy	1425 Co
Brass	Copper and zinc alloy	1000 Co
Nickel silver	Alloy of copper, zinc and nickel	1100 So
Nichrome	Alloy of nickel, chromium, silicon, iron, manganese and aluminum	1400 So
Steel	Iron-carbon alloy	1300 Co – 1500 Co
Fechral	Alloy of chromium, iron, aluminum, manganese and silicon	1460 So
Cast iron	Iron-carbon alloy	1100 Co – 1300 Co

Refractory metals

The temperature of refractory metals is above 1600°C. These are tungsten, titanium, platinum, chromium and others. They are used as light sources, machine parts, lubricants, and in the nuclear industry. They are used to make wires, high-voltage wires, and are used to melt other metals with a lower melting point. Platinum begins to transition from solid to liquid at a temperature of 1769 degrees, and tungsten at a temperature of 3420°C.

Mercury is the only metal that is in a liquid state under normal conditions, namely, normal atmospheric pressure and average ambient temperature. The melting point of mercury is minus 39°C. This metal and its vapors are poisonous, so it is used only in closed containers or in laboratories. A common use of mercury is as a thermometer to measure body temperature.

Each metal and alloy has its own unique set of physical and chemical properties, not least of which is the melting point. The process itself means the transition of a body from one state of aggregation to another, in this case, from a solid crystalline state to a liquid one. To melt a metal, it is necessary to apply heat to it until the melting temperature is reached. With it, it can still remain in a solid state, but with further exposure and increased heat, the metal begins to melt. If the temperature is lowered, that is, some of the heat is removed, the element will harden.

The highest melting point among metals belongs to tungsten: it is 3422C o, the lowest is mercury: the element melts at -39C o. As a rule, it is not possible to determine the exact value for alloys: it can vary significantly depending on the percentage of components. They are usually written as a number interval.

Table of refractory metals and alloys (over 1600C o)

Item name	Latin designation	Temperatures
Item name	Latin designation	Melting	Boiling
Tungsten	W	3420 Co	5555 Co
Titanium	Ti	1680 So	3300 So
Iridium	Ir	2447 Co	4428 Co
Osmium	Os	3054 Co	5012 Co
Platinum	Pt	1769.3 Co	3825 Co
Rhenium	Re	3186 Co	5596 Co
Chromium	Cr	1907 Co	2671 Co
Rhodium	Rh	1964 Co	3695 Co
Ruthenium	Ru	2334 Co	4150 Co
Hafnium	Hf	2233 Co	4603 Co
Tantalum	Ta	3017 Co	5458 Co
Technetium	Tc	2157 Co	4265 Co
Thorium	Th	1750 So	4788 Co
Vanadium	V	1910 Co	3407 Co
Zirconium	Zr	1855 Co	4409 Co
Niobium	Nb	2477 Co	4744 Co
Molybdenum	Mo	2623 Co	4639 Co
Hafnium carbides	3890 Co
Niobium carbides	3760 Co
Titanium carbides	3150 Co
Zirconium carbides	3530 Co

Specific heat of fusion of certain substances

Information on specific heat values for a specific substance can be found in book reference books or in electronic versions on Internet resources. They are usually presented in table form:

Specific heat of fusion of substances

Substance	105 * J/kg	kcal/kg	Substance	105 * J/kg	kcal/kg
Aluminum	3,8	92	Mercury	0,1	3,0
Iron	2,7	65	Lead	0,3	6,0
Ice	3,3	80	Silver	0,87	21
Copper	1,8	42	Steel	0,8	20
Naphthalene	1,5	36	Zinc	1,2	28
Tin	0,58	14	Platinum	1,01	24,1
Paraffin	1,5	35	Gold	0,66	15,8

One of the most refractory substances is tantalum carbide - TаC. It melts at a temperature of 39900C. TAC coatings are used to protect metal molds in which aluminum parts are cast.

Rice. 3. Metal melting process.

Which metal has the highest melting point

Tungsten is the most refractory metal, 3422 °C (6170 °F).
A hard, refractory, fairly heavy material of light gray color that has a metallic sheen. It is difficult to machine. At room temperature it is quite fragile and breaks. The fragility of the metal is associated with contamination with carbon and oxygen impurities.

Note! Technically, pure metal at temperatures above four hundred degrees Celsius becomes very ductile. Demonstrates chemical inertness and is reluctant to react with other elements. It occurs in nature in the form of such complex minerals as: hübnerite, scheelite, ferberite and wolframite.

Tungsten can be obtained from its ore, through complex chemical processing, as a powder. Using pressing and sintering, it is used to create parts of regular shape and bars.

Tungsten is an extremely resistant element to any temperature influences. For this reason, tungsten could not be softened for more than a hundred years. There was no furnace that could heat up to several thousand degrees Celsius. Scientists have been able to prove that this is the most refractory metal. Although there is an opinion that seaborgium, according to some theoretical data, has greater refractoriness, this is only an assumption, since it is a radioactive element and has a short lifespan.