Metallurgical Processes: Thermodynamics
Metallurgical processes are physical and chemical procedures used to alter the properties of metals and other materials. Thermodynamics is a branch of science which studies the energy changes that take place within a system under a given set of circumstances. It generally involves calculating the energy stored within a metal and the available energy for work, which allows metallurgists to predict how metal composition and material densities will be affected by heat processes such as melting and cooling.
Heat is a form of energy which is released when molecules in a system rearrange into more stable states. In thermodynamic systems, molecules exchange energy as they interact. During these interactions, the potential energy stored in molecules fluctuates randomly. When the molecules absorb or release energy, they may react chemically or physically with other molecules in less energetically favorable ways.
Heat energy can behave adiabatically, meaning that it can be both absorbed and released without any other energy being exchanged with the environment. In metallurgical processes, the effects of adiabatic energy are fairly common, as metals undergoing heat treatment are often stored in an insulated furnace to minimize heat exchange.
The release or absorption of energy within the system is indicative of an increase or decrease in entropy. entropy is a measurement of the involuntary or random processes of heat exchange. A change in entropy indicates the magnitude of random interactions within the system. In traditional thermodynamic processes, entropy can be calculated as the total heat transfer divided by the surrounding temperature.
Heat is a form of energy that also influences the composition of a material. As heat is introduced to a system, the molecules may react in different ways and eventually settle into new arrangements with less stable potential energy. This rearrangement of molecules is known as phase transformation. It is one of the primary factors that impact the thermodynamic properties of a material, such as its melting point and boiling point.
When molecules are heated, they may also form new bonds or break existing ones. This is known as a chemical reaction because it involves the formation of new compounds. In metallurgical processes, these chemical reactions are often utilized to change the composition of metals and alloys. For instance, when a metal is heated in the presence of an oxidizing agent, it is possible to oxidize existing compounds and create new ones.
The thermodynamic properties of metals vary with temperature. At higher temperatures, metals become more malleable and their melting and boiling points are decreased. Conversely, at lower temperatures, most metals become less malleable and their melting and boiling points are raised. By manipulating the temperature of metals through the use of heating or cooling, it is possible to alter the physical and chemical properties of metals and alloys.
Thermodynamic processes are integral components of metallurgy and can be used to manipulate and improve the properties of metals and alloys. Through the use of heat, it is possible to induce phase transformations, cause chemical reactions, and alter the temperature-dependent properties of materials. By understanding the principles and laws of thermodynamics, metallurgists can formulate processes and procedures to manipulate and enhance the physical and chemical properties of metals and alloys for varied applications.
