Thermodynamic Principles of Metallurgy - GeeksforGeeks (2023)

Physical Chemistry is a branch of physics and chemistry that combines the two disciplines. This is when the concept of thermodynamics comes to an end. Thermodynamics is a branch of physics that studies the link between thermal energy, such as heat, and other types of energy. The study of energy transfer that occurs during chemical and physical transformations is known as thermodynamics. It also enables us to forecast and track these shifts.

Thermodynamics in Metallurgy

When it comes to metallurgy, Gibbs Free Energy is the most important thermodynamic notion to understand. Gibbs Free Energy determines whether a process will occur spontaneously or not in thermodynamics. The letter ΔG. If the value of ΔG is negative, the reaction will happen on its own. To arrive at ΔG, we’ll look at two equations.


The change in enthalpy is denoted by ΔH. An endothermic reaction will be represented by a positive value, while an exothermic reaction will be represented by a negative value. As a result, when the reaction is exothermic, ΔG is negative. Entropy, or the unpredictability of molecules, is denoted by the letter ΔS. When the state of the matter changes, this changes dramatically. Another equation that connects Gibbs Free Energy and the equilibrium constant is

ΔG° = RTlnKeq

The equilibrium constant is Keq. The active mass of products is divided by the active mass of reactants to arrive at this figure. The universal gas component is R. The equilibrium value must now be kept positive in order to get a negative value of ΔG (which is desirable).

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Ellingham Diagram

Thermodynamic Principles of Metallurgy - GeeksforGeeks (1)

An Ellingham diagram depicts the relationship between temperature and a compound’s stability. It’s a graphical illustration of the Gibbs Energy Flow. The Ellingham diagram is used in metallurgy to plot the reduction process equations. This aids us in determining the best reducing agent to use when reducing oxides to produce pure metals. Let’s take a look at some of the Ellingham Diagram’s most crucial features.

  1. ΔG is plotted in relation to temperature in this graph. The entropy is represented by the slope of the curve, whereas the enthalpy is represented by the intercept.
  2. As you may be aware, the ΔH (enthalpy) is unaffected by temperature.
  3. The temperature has no effect on ΔS, which is the entropy. However, there is a stipulation that no phase shift should occur.
  4. The temperature will be plotted on the Y-axis, while the ΔG will be plotted on the X-axis.
  5. Metals with curves near the bottom of the diagram are less common than metals found higher up.

The reaction of metal with air can be summed up as follows:

M(s) + O2(g) → MO(s)

When it comes to reducing metal oxides, the ΔH is usually always negative (exothermic). ΔS is also negative because we are going from a gaseous to a solid-state in the reaction (as seen above). As a result, as the temperature rises, the value of TΔS rises as well, and the reaction slope rises.

Observations from the Ellingham diagram.

  1. The slope is positive for the majority of metal oxide production. It is possible to explain it as follows. The creation of metal oxides consumes oxygen gas, resulting in a decrease in unpredictability. As a result, ΔS becomes negative, and the term TΔS in the straight line equation becomes positive.
  2. Carbon monoxide formation is shown by a straight line with a negative slope. In this scenario, ΔS is positive because the consumption of one mole of oxygen gas results in the formation of two moles of CO gas. It implies that CO becomes more stable at higher temperatures.
  3. As the temperature rises, the ΔG value for the creation of metal oxide becomes less negative until it reaches zero at a certain point. Below this temperature, ΔG is negative and the oxide is stable; above this temperature, ΔG is positive and the oxide is unstable. This overall pattern shows that as temperatures rise, metal oxides become less stable and decompose more easily.
  4. Some metal oxides, such as MgO and HgO, have a sharp change in slope at a specific temperature. This is because of a phase shift (melting or evaporation).

Limitations of Ellingham Diagram

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  1. Ellingham diagrams are built solely on thermodynamic considerations. It provides information on a reaction’s thermodynamic feasibility. It provides no information regarding the rate of the reaction. Furthermore, it provides no indication of the probability of other reactions occurring.
  2. It also lacks comprehensive information on the oxides and their formations. Let’s say there’s the possibility of more than one oxide. This scenario is not represented in the diagram.
  3. The interpretation of ΔG is predicated on the assumption that the reactants and products are in equilibrium, which is not necessarily true.

Uses of Ellingham Diagram

  1. On the graph, the Ellingham curve is lower than that of most other metals, such as iron. This effectively suggests that all of the metals above it in the graph can be utilised as a reducing agent for their oxides. Because aluminium oxide is more stable, it is utilised in the thermite process to extract chromium.
  2. A blast furnace is used to separate iron from its oxide. In the furnace, the ore is mixed with coke and limestone. The reduction of iron oxides takes place at a variety of temperatures. The temperature in the bottom part of the furnace is substantially higher than in the top. Thermodynamics was used to explain the reactions, which led to the development of this technique.
  3. At the top of the diagram is the Ellingham diagram for the formation of Ag2O and HgO, with breakdown temperatures of 600 and 700 K, respectively. It means that these oxides are unstable at low temperatures and will break down when heated, even if no reducing agent is present.
  4. The Ellingham diagram is used to forecast the thermodynamic feasibility of reducing oxides of one metal by oxides of another. Any metal can diminish the oxides of other metals in the figure above it. In the Ellingham figure, for example, the formation of chromium oxide is above that of aluminium, indicating that Al2O3 is more stable than Cr2O3. As a result, aluminium can be utilised as a reducing agent to reduce chromic oxide. It cannot, however, be used to diminish the oxides of magnesium and calcium, which are in a lower position than aluminium oxide.
  5. Because the carbon line crosses the lines of many metal oxides, it can decrease all of them at sufficiently high temperatures. Let’s look at the thermodynamically favourable circumstances for iron oxide reduction by carbon. Around 1000 K, the Ellingham diagram for the production of FeO and CO intersects. Below this temperature, the carbon line is above the iron line, indicating that FeO is more stable than CO and so the reduction is not thermodynamically viable at this temperature range. However, above 1000 K, the carbon line is below the iron line, allowing us to use coke as a reducing agent. The free energy calculation that follows confirms that the decrease is thermodynamically advantageous.

Sample Questions

Question 1: How is metallurgy used for production?


In production engineering, metallurgy deals with the manufacturing of metallic components for use in technical or consumer products. Manufacturing, shape, heat treatment, and product surface treatment all fall under this category.

Question 2: What is extractive metallurgy?


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Extractive metallurgy is the process of removing valuable metals from an ore and purifying the retrieved raw metals into a purer form. The ore must be reduced physically, chemically, or electrolytically to convert a metal oxide or sulphide to a purer metal. The three principal streams of interest to extractive metallurgists are feed, concentrate (metal oxide/sulphide), and tailings (waste).

Question 3: What is metallurgy?


The physical and chemical properties of intermetallic compounds, metallic elements, and alloy mixes are studied in metallurgy, a branch of materials science and engineering. Metallurgy is the science and technology of metals, i.e. how science is used to metal manufacture and the engineering of metal components used in consumer and industrial products. Metallurgy is distinct from minecrafting as a skill. For technological advancement, metalworking is reliant on metallurgy, much as medicine is reliant on medical science.

Question 4: Write a note on metal and its alloys


(Video) Metallurgy | Thermodynamics of Metallurgy | L3 | Medhavi NEET 2022/23 | Anoop Vashishta

Aluminium, chromium, copper, iron, magnesium, nickel, titanium, zinc, and silicon are examples of engineering metals. These metals, with the exception of silicon, are the most typically used in alloys. Steels and cast irons are part of the iron-carbon alloy system, which has gotten a lot of attention. Plain carbon steels (those with almost all carbon as an alloying ingredient) are used in low-cost, high-strength applications where weight and corrosion aren’t an issue. Cast irons, such as ductile iron, are also part of the iron-carbon system. Iron-manganese-chromium alloys are used in non-magnetic applications such as directional drilling (Hadfield-type steels).

Question 5: What are some significant Exceptions in Ellingham Diagram?


Following are some significant Exceptions in Ellingham Diagram:

  • C(s) + O2 (g) → CO2 (g): Solids have a minimal entropy. As a result, one molecule of gas yields one molecule of gas. As a result, there is virtually little net entropy. As a result, there will be no slope and the surface will be perfectly horizontal.
  • 2C (s)+ O2 (g) → 2CO (g): One mole of gas yields two moles of gas as a result of this reaction. As a result, the entropy will be positive in this case. As a result, this curve will begin to decline.

My Personal Notesarrow_drop_up

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What is thermodynamic principles of metallurgy? ›

Thermodynamics in Metallurgy

Keq is the equilibrium constant. It is calculated by dividing the active mass of products by the active mass of reactants. R is the universal gas component. Now to attain a negative value of ΔG (which is desirable) the value of the equilibrium must be kept positive.

What is metallurgical thermodynamics? ›

It is the subject which dealing with the relation between heat and motion. Development of metallurgical Thermodynamic occurs due to the application of chemical thermodynamics to the metals & materials which later on known as Thermodynamics of materials.

Why is thermodynamics important in metallurgy? ›

The main use of thermodynamics in physical metallurgy is to allow the prediction of whether an alloy is in equilibrium. In considering phase transformations, we are always concerned with changes towards equilibrium. And thermodynamics is therefore a very powerful tool.

What are the basic principles of thermodynamics? ›

thermodynamics, science of the relationship between heat, work, temperature, and energy. In broad terms, thermodynamics deals with the transfer of energy from one place to another and from one form to another. The key concept is that heat is a form of energy corresponding to a definite amount of mechanical work.

What are the principles of metallurgy? ›

This course teaches 3 key principles about metallurgy:

1) The microscopic structures present in metals. 2) How microstructure and alloy composition influence metal strength. 3) How composition, cold-working, and heat treating are used to modify metal microstructure to obtain desired mechanical properties.

What are the 4 types of thermodynamic process explain each? ›

There are several types of thermodynamic processes, including (a) isothermal, where the system's temperature is constant; (b) adiabatic, where no heat is exchanged by the system; (c) isobaric, where the system's pressure is constant; and (d) isochoric, where the system's volume is constant.

What are the three types of thermodynamic? ›

There are three types of systems in thermodynamics: open, closed, and isolated. An open system can exchange both energy and matter with its surroundings.

What are the three types of metallurgy? ›

Metallurgical Engineering is a broad field that deals with all sorts of metal-related areas. The three main branches of this major are physical metallurgy, extractive metallurgy, and mineral processing.

What are the two types of metallurgy? ›

The science of metallurgy is further subdivided into two broad categories: chemical metallurgy and physical metallurgy. Chemical metallurgy is chiefly concerned with the reduction and oxidation of metals, and the chemical performance of metals.

What is the main function of thermodynamics? ›

Thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy. Four basic laws have been established. The first law states that the amount of energy added to a system is equal to the sum of its increase in heat energy and the work done on the system.

What are the main objectives of thermodynamics? ›

The objectives of thermodynamics are: To improve the efficiency of a process for the transformation between energy and work. To study energy conversion in different forms. To study the entropy of a system.

What are main applications of thermodynamics? ›

Thermal power plants, nuclear power plants, hydroelectric power plants, and power plants based on renewable energy sources such as solar, wind, geothermal, tides, and water waves are all studied in thermodynamics.

How many principles are there in thermodynamics? ›

Traditionally, thermodynamics has recognized three fundamental laws, simply named by an ordinal identification, the first law, the second law, and the third law.

Who is father of thermodynamics? ›

Nicolas Léonard Sadi Carnot is often described as the “Father of Thermodynamics.”

Is there 3 laws of thermodynamics? ›

1st Law of Thermodynamics - Energy cannot be created or destroyed. 2nd Law of Thermodynamics - For a spontaneous process, the entropy of the universe increases. 3rd Law of Thermodynamics - A perfect crystal at zero Kelvin has zero entropy.

What are the four process of metallurgy? ›

Concentration of the or ORE DRESSING or ENRICHMENT OF THE ORE(gangue- to remove the earthly impurities) Converting into oxides by roasting(sulphide ores in presence of o2and calcination of the carbonate ores in limited amount of o2) Reduction of metaloxides into metals.

What are the types of metallurgy? ›

The three main branches of Metallurgical Engineering Course are physical metallurgy, extractive metallurgy and mineral processing. Physical metallurgy deals with problem solving i.e. development of metallic alloys needed for different types of manufacturing and construction.

Who is called Father of Indian metallurgy? ›

An influential Indian metallurgist and alchemist was Nagarjuna (born 931). He wrote the treatise Rasaratnakara that deals with preparations of rasa (mercury) compounds. It gives a survey of the status of metallurgy and alchemy in the land.

What are the 5 thermodynamic processes? ›

There are four types of thermodynamic processes, they are,
  • Isothermal process.
  • Isobaric process.
  • Isochoric process.
  • Adiabatic process.

What are the 2 classification of thermodynamics? ›

Thermodynamic systems may be classified into the following groups: Closed system. Open system.

What are the two types of thermodynamic instruments? ›

There are two types of thermodynamic instruments, the meter and the reservoir. A thermodynamic meter is any device which measures any parameter of a thermodynamic system.

What is 3rd Law of Thermodynamics called? ›

The third law was developed by chemist Walther Nernst during the years 1906–12, and is therefore often referred to as Nernst's theorem or Nernst's postulate. The third law of thermodynamics states that the entropy of a system at absolute zero is a well-defined constant.

What are the characteristics of thermodynamics? ›

Thermodynamic characteristics are detrimental factors to describe the state of a system. A thermodynamic property is a particularity or a characteristic that allows the changes of the work system. Thermodynamics is a part of physics that establishes relations between work, heat and different forms of energy.

Why is it called thermodynamics? ›

"Thermodynamics" comes from the Greek words "therme" which means heat and "dynamikos" which means force, or power. So, "Thermodynamics" is essentially the study of forces due to heat or heat due to forces.

What are the 3 steps of metallurgy? ›

Steps in Metallurgical Process
  • Crushing and grinding the ore.
  • The concentration of ore, is also known as ore enrichment.
  • Metal extraction from concentrated ore.
  • Impure metals are refined or purified.

What is the 5 steps of metallurgy? ›

Answer: Metallurgy consists of three general steps: (1) mining the ore, (2) separating and concentrating the metal or the metal-containing compound, and (3) reducing the ore to the metal. Additional processes are sometimes required to improve the mechanical properties of the metal or increase its purity.

What are the applications of metallurgy? ›

They form a very essential part of manufacturing modern aircraft, vehicles of transportation (automobiles, trains, ships) and recreational vehicles; buildings; implantable devices; cutlery and cookware; coins and jewelry; firearms; and musical instruments.

Who is called metallurgy? ›

metallurgy, art and science of extracting metals from their ores and modifying the metals for use. Metallurgy customarily refers to commercial as opposed to laboratory methods.

What are the types of test in metallurgy? ›

Subtypes include:
  • Bend test.
  • Impact test – Further categorised as Charpy test and Izod test.
  • Hardness test.
  • Tensile test.
  • Fatigue test.
  • Corrosion resistance test.
  • Wear test.

Why do we study metallurgy? ›

Metallurgical engineering is the study of metals and how metals can be safely transformed into products that benefit humanity such as surgical implants, computer chips, cars, materials for space exploration, and more.

What is the first law of thermodynamics? ›

The first law of thermodynamics is based on the law of conservation of energy, which states that energy cannot be created or destroyed, but can be transferred from one form to another.

What is thermodynamics and its importance? ›

Thermodynamics is a very important branch of both physics and chemistry. It deals with the study of energy, the conversion of energy between different forms and the ability of energy to do work.

What is the important first law of thermodynamics? ›

The first law of thermodynamics, arguably the most important, is an expression of the principle of conservation of energy. Consistent with this principle, the first law expresses that energy can be transformed (i.e. changed from one form to another), but cannot be created or destroyed.

What are limitations of thermodynamics? ›

The limitation of the first law of thermodynamics is that it does not say anything about the direction of flow of heat. It does not say anything whether the process is a spontaneous process or not. The reverse process is not possible. In actual practice, the heat doesn't convert completely into work.

What are the types of thermodynamics functions? ›

The following are considered to be state functions in thermodynamics:
  • Mass.
  • Energy (E) Enthalpy (H) Internal energy (U) Gibbs free energy (G) Helmholtz free energy (F) Exergy (B)
  • Entropy (S)
  • Pressure (P)
  • Temperature (T)
  • Volume (V)
  • Chemical composition.
  • Pressure altitude.

What are the branches of thermodynamics? ›

The study of Thermodynamics is classified into several branches listed below:
  • Classical Thermodynamics. ...
  • Statistical Thermodynamics. ...
  • Chemical Thermodynamics. ...
  • Equilibrium Thermodynamics. ...
  • Non-equilibrium Thermodynamics. ...
  • Thermodynamic Systems. ...
  • Heat. ...
  • Work.
24 Aug 2022

What are real life examples of thermodynamics? ›

Heating and cooling systems in our homes and other buildings, engines that power our motor vehicles, even the design of buildings and vehicles, all incorporate information from thermodynamics to make them perform well.

What are the benefits of thermodynamics? ›

Thermodynamics gives the foundation for heat engines, power plants, chemical reactions, refrigerators, and many more important concepts that the world we live in today relies on. Beginning to understand thermodynamics requires knowledge of how the microscopic world operates.

What are the 7 properties considered in thermodynamics? ›

Example: mass, volume, internal energy, enthalpy, heat capacity, entropy, Gibbs free energy.

Who discovered the 4 laws of thermodynamics? ›

Both choices were arbitrary. However, although Thomson provided a consistent driving force to develop thermodynamics, in 1850 Clausius actually developed thermodynamics [4].

Who gave the 1st law of thermodynamics? ›

Explanation: Around 1850 Rudolf Clausius and William Thomson (Kelvin) developed the first law of thermodynamics, which states that the "total energy of an isolated system is constant".

Who gave 2 law of thermodynamics? ›

Scottish physicist William Thomson, also known as Lord Kelvin, and German physicist Rudolf Clausius developed the second law of thermodynamics in the mid-19th century. Thomson and Clausius phrased the law in slightly different ways, but the two versions were soon proved equivalent.

WHO said the first law of thermodynamics? ›

Around 1850 Rudolf Clausius and William Thomson (Kelvin) stated both the First Law - that total energy is conserved - and the Second Law of Thermodynamics.

Why is it called Zeroth Law of Thermodynamics? ›

Assertion :The zeroth law of thermodynamics was known before law I of thermodynamics. Reason: The zeroth law concerning thermal equilibrium was appeared after three laws (I, II and III) of termodynamics and thus was named as zeroth law.

What is the 2nd Law of Thermodynamics called? ›

His formulation of the second law, which was published in German in 1854, is known as the Clausius statement: Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time. The statement by Clausius uses the concept of 'passage of heat'.

What is the law of entropy? ›

The second law of thermodynamics states that the total entropy of a system either increases or remains constant in any spontaneous process; it never decreases.

What is thermodynamic process in simple words? ›

Thermodynamic processes are the movement of heat energy within or between systems. A Thermodynamic system is a specific space or macroscopic region in the universe, whose state can be expressed in terms of pressure, temperature, and volume, and in which one or more than one Thermodynamic process occurs.

What is thermodynamics explain? ›

Thermodynamics in physics is a branch that deals with heat, work and temperature, and their relation to energy, radiation and physical properties of matter. To be specific, it explains how thermal energy is converted to or from other forms of energy and how matter is affected by this process.

What is thermodynamic process in mechanical engineering? ›

(1)A Thermodynamic process is a process in which the thermodynamic state of a system is changed. A change in a system is defined by a passage from an initial to a final state of thermodynamic equilibrium. In classical thermodynamics, the actual course of the process is not the primary concern, and often is ignored.

What are the first 3 laws of thermodynamics? ›

1st Law of Thermodynamics - Energy cannot be created or destroyed. 2nd Law of Thermodynamics - For a spontaneous process, the entropy of the universe increases. 3rd Law of Thermodynamics - A perfect crystal at zero Kelvin has zero entropy.

What are different types of thermodynamics process? ›

The four types of thermodynamic process are isobaric, isochoric, isothermal and adiabatic.

What is importance of thermodynamics? ›

Thermodynamics gives the foundation for heat engines, power plants, chemical reactions, refrigerators, and many more important concepts that the world we live in today relies on. Beginning to understand thermodynamics requires knowledge of how the microscopic world operates.

What is thermodynamics formula? ›

H = U + PV. ΔH = ΔU + PΔV (constant pressure) ΔU = ΔH - PΔV.

What are the two types of thermodynamic applications? ›

Thermodynamics: Important Terms

The various types of systems are: Open System: The systems where the exchange of energy takes place are open systems. Closed System: It is a system where energy can be exchanged only with the surroundings and not the matter.

What is the First Law of Thermodynamics in mechanical engineering? ›

The First Law of Thermodynamics states that heat is a form of energy, and thermodynamic processes are therefore subject to the principle of conservation of energy. This means that heat energy cannot be created or destroyed.

What is the First Law of Thermodynamics state? ›

The First Law of Thermodynamics states that energy cannot be created or destroyed; it can only be converted from one form to another.

What are the two thermodynamic properties? ›

The thermodynamic properties of the system are divided into two general classes: Extensive property. Intensive property.

What are the applications of thermodynamics? ›

Thermal power plants, nuclear power plants, hydroelectric power plants, and power plants based on renewable energy sources such as solar, wind, geothermal, tides, and water waves are all studied in thermodynamics.


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