Liquidus and solidus

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While chemically pure materials have a single melting point, chemical mixtures often partially melt at the solidus temperature (TS or Tsol), and fully melt at the higher liquidus temperature (TL or Tliq). The solidus is always less than or equal to the liquidus, but they need not coincide. If a gap exists between the solidus and liquidus it is called the freezing range, and within that gap, the substance consists of a mixture of solid and liquid phases (like a slurry). Such is the case, for example, with the olivine (forsterite-fayalite) system, which is common in Earth's mantle. [1]

Contents

Definitions

The equilibrium phase diagram of a solid solution of made up of mixtures of a and b. The upper curve is the line of liquidus, and the lower curve is the line of solidus. Solid solution.svg
The equilibrium phase diagram of a solid solution of made up of mixtures of α and β. The upper curve is the line of liquidus, and the lower curve is the line of solidus.

In chemistry, materials science, and physics, the liquidus temperature specifies the temperature above which a material is completely liquid, [2] and the maximum temperature at which crystals can co-exist with the melt in thermodynamic equilibrium. The solidus is the locus of temperatures (a curve on a phase diagram) below which a given substance is completely solid (crystallized). The solidus temperature, specifies the temperature below which a material is completely solid, [2] and the minimum temperature at which a melt can co-exist with crystals in thermodynamic equilibrium.

Liquidus and solidus are mostly used for impure substances (mixtures) such as glasses, metal alloys, ceramics, rocks, and minerals. Lines of liquidus and solidus appear in the phase diagrams of binary solid solutions, [2] as well as in eutectic systems away from the invariant point. [3]

When distinction is irrelevant

For pure elements or compounds, e.g. pure copper, pure water, etc. the liquidus and solidus are at the same temperature, and the term melting point may be used.

There are also some mixtures which melt at a particular temperature, known as congruent melting. One example is eutectic mixture. In a eutectic system, there is particular mixing ratio where the solidus and liquidus temperatures coincide at a point known as the invariant point. At the invariant point, the mixture undergoes a eutectic reaction where both solids melt at the same temperature. [3]

Modeling and measurement

There are several models used to predict liquidus and solidus curves for various systems. [4] [5] [6] [7]

Detailed measurements of solidus and liquidus can be made using techniques such as differential scanning calorimetry and differential thermal analysis. [8] [9] [10] [11]

Effects

Liquidus temperature curve in the binary glass system SiO2-Li2O SiO2 Li2O.GIF
Liquidus temperature curve in the binary glass system SiO2-Li2O

For impure substances, e.g. alloys, honey, soft drink, ice cream, etc. the melting point broadens into a melting interval. If the temperature is within the melting interval, one may see "slurries" at equilibrium, i.e. the slurry will neither fully solidify nor melt. This is why new snow of high purity on mountain peaks either melts or stays solid, while dirty snow on the ground in cities tends to become slushy at certain temperatures. Weld melt pools containing high levels of sulfur, either from melted impurities of the base metal or from the welding electrode, typically have very broad melting intervals, which leads to increased risk of hot cracking.

Behavior when cooling

Above the liquidus temperature, the material is homogeneous and liquid at equilibrium. As the system is cooled below the liquidus temperature, more and more crystals will form in the melt if one waits a sufficiently long time, depending on the material. Alternately, homogeneous glasses can be obtained through sufficiently fast cooling, i.e., through kinetic inhibition of the crystallization process.

The crystal phase that crystallizes first on cooling a substance to its liquidus temperature is termed primary crystalline phase or primary phase. The composition range within which the primary phase remains constant is known as primary crystalline phase field.

The liquidus temperature is important in the glass industry because crystallization can cause severe problems during the glass melting and forming processes, and it also may lead to product failure. [12]

See also

Related Research Articles

<span class="mw-page-title-main">Melting</span> Material phase change

Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which increases the substance's temperature to the melting point. At the melting point, the ordering of ions or molecules in the solid breaks down to a less ordered state, and the solid melts to become a liquid.

<span class="mw-page-title-main">Phase (matter)</span> Region of uniform physical properties

In the physical sciences, a phase is a region of material that is chemically uniform, physically distinct, and (often) mechanically separable. In a system consisting of ice and water in a glass jar, the ice cubes are one phase, the water is a second phase, and the humid air is a third phase over the ice and water. The glass of the jar is another separate phase.

<span class="mw-page-title-main">Solder</span> Alloy used to join metal pieces

Solder is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable for use as solder should have a lower melting point than the pieces to be joined. The solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solder used in making electrical connections also needs to have favorable electrical characteristics.

<span class="mw-page-title-main">Magma</span> Hot semifluid material found beneath the surface of Earth

Magma is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and gas bubbles.

<span class="mw-page-title-main">Melting point</span> Temperature at which a solid turns liquid

The melting point of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.

<span class="mw-page-title-main">Phase transition</span> Physical process of transition between basic states of matter

In chemistry, thermodynamics, and other related fields, a phase transition is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of matter: solid, liquid, and gas, and in rare cases, plasma. A phase of a thermodynamic system and the states of matter have uniform physical properties. During a phase transition of a given medium, certain properties of the medium change as a result of the change of external conditions, such as temperature or pressure. This can be a discontinuous change; for example, a liquid may become gas upon heating to its boiling point, resulting in an abrupt change in volume. The identification of the external conditions at which a transformation occurs defines the phase transition point.

<span class="mw-page-title-main">Phase diagram</span> Chart used to show conditions at which physical phases of a substance occur

A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions at which thermodynamically distinct phases occur and coexist at equilibrium.

<span class="mw-page-title-main">Eutectic system</span> Mixture with a lower melting point than its constituents

A eutectic system or eutectic mixture is a homogeneous mixture that has a melting point lower than those of the constituents. The lowest possible melting point over all of the mixing ratios of the constituents is called the eutectic temperature. On a phase diagram, the eutectic temperature is seen as the eutectic point.

<span class="mw-page-title-main">Freezing</span> Phase transition in which a liquid turns into a solid due to a decrease in thermal energy

Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. In accordance with the internationally established definition, freezing means the solidification phase change of a liquid or the liquid content of a substance, usually due to cooling.

<span class="mw-page-title-main">Fractional freezing</span> Separating components of a mixture by their melting points

Fractional freezing is a process used in process engineering and chemistry to separate substances with different melting points. It can be done by partial melting of a solid, for example in zone refining of silicon or metals, or by partial crystallization of a liquid, as in freeze distillation, also called normal freezing or progressive freezing. The initial sample is thus fractionated.

<span class="mw-page-title-main">Crystallization</span> Process by which a solid with a highly organized atomic or molecular structure forms

Crystallization is the process by which solid forms, where the atoms or molecules are highly organized into a structure known as a crystal. Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposition directly from a gas. Attributes of the resulting crystal depend largely on factors such as temperature, air pressure, and in the case of liquid crystals, time of fluid evaporation.

Differential thermal analysis (DTA) is a thermoanalytic technique that is similar to differential scanning calorimetry. In DTA, the material under study and an inert reference are made to undergo identical thermal cycles, while recording any temperature difference between sample and reference. This differential temperature is then plotted against time, or against temperature. Changes in the sample, either exothermic or endothermic, can be detected relative to the inert reference. Thus, a DTA curve provides data on the transformations that have occurred, such as glass transitions, crystallization, melting and sublimation. The area under a DTA peak is the enthalpy change and is not affected by the heat capacity of the sample.

A solid solution, a term popularly used for metals, is a homogeneous mixture of two different kinds of atoms in solid state and having a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solution" is used to describe the intimate mixing of components at the atomic level and distinguishes these homogeneous materials from physical mixtures of components. Two terms are mainly associated with solid solutions – solvents and solutes, depending on the relative abundance of the atomic species.

In geology, igneous differentiation, or magmatic differentiation, is an umbrella term for the various processes by which magmas undergo bulk chemical change during the partial melting process, cooling, emplacement, or eruption. The sequence of magmas produced by igneous differentiation is known as a magma series.

<span class="mw-page-title-main">Polyamorphism</span> Ability of a substance to exist in more than one distinct amorphous state

Polyamorphism is the ability of a substance to exist in several different amorphous modifications. It is analogous to the polymorphism of crystalline materials. Many amorphous substances can exist with different amorphous characteristics. However, polyamorphism requires two distinct amorphous states with a clear, discontinuous (first-order) phase transition between them. When such a transition occurs between two stable liquid states, a polyamorphic transition may also be referred to as a liquid–liquid phase transition.

<span class="mw-page-title-main">Fractional crystallization (geology)</span> Process of rock formation

Fractional crystallization, or crystal fractionation, is one of the most important geochemical and physical processes operating within crust and mantle of a rocky planetary body, such as the Earth. It is important in the formation of igneous rocks because it is one of the main processes of magmatic differentiation. Fractional crystallization is also important in the formation of sedimentary evaporite rocks or simply fractional crystallization is the removal of early formed crystals from an Original homogeneous magma so that the crystals are prevented from further reaction with the residual melt.

<span class="mw-page-title-main">Fractional crystallization (chemistry)</span> Method for refining substances based on differences in their solubility

In chemistry, fractional crystallization is a stage-wise separation technique that relies on the liquid-solid phase change. It fractionates via differences in crystallization temperature and enables the purification of multi-component mixtures, as long as none of the constituents can act as solvents to the others. Due to the high selectivity of the solid - liquid equilibrium, very high purities can be achieved for the selected component.

In petrology, micrographic texture is a fine-grained intergrowth of quartz and alkali feldspar, interpreted as the last product of crystallization in some igneous rocks which contain high or moderately high percentages of silica. Micropegmatite is an outmoded terminology for micrographic texture.

<span class="mw-page-title-main">Binary compounds of silicon</span> Any binary chemical compound containing just silicon and another chemical element

Binary compounds of silicon are binary chemical compounds containing silicon and one other chemical element. Technically the term silicide is reserved for any compounds containing silicon bonded to a more electropositive element. Binary silicon compounds can be grouped into several classes. Saltlike silicides are formed with the electropositive s-block metals. Covalent silicides and silicon compounds occur with hydrogen and the elements in groups 10 to 17.

<span class="mw-page-title-main">Bismuth–indium</span>

The elements bismuth and indium have relatively low melting points when compared to other metals, and their alloy bismuth–indium (Bi–In) is classified as a fusible alloy. It has a melting point lower than the eutectic point of the tin–lead alloy. The most common application of the Bi-In alloy is as a low temperature solder, which can also contain, besides bismuth and indium, lead, cadmium, and tin.

References

  1. ↑ Herzberg, Claude T. (1983). "Solidus and liquidus temperatures and mineralogies for anhydrous garnet-lherzolite to 15 GPa". Physics of the Earth and Planetary Interiors. Elsevier BV. 32 (2): 193–202. Bibcode:1983PEPI...32..193H. doi:10.1016/0031-9201(83)90139-5. ISSN   0031-9201.
  2. 1 2 3 Askeland, Donald R.; Fulay, Pradeep P. (2008-04-23). Essentials of Materials Science & Engineering (2nd ed.). Toronto: Cengage Learning. p. 305. ISBN   978-0-495-24446-2.
  3. 1 2 Callister, William D.; Rethwisch, David G. (2008). Fundamentals of Materials Science and Engineering: An Integrated Approach (3rd ed.). John Wiley & Sons. pp. 356–358. ISBN   978-0-470-12537-3.
  4. ↑ Safarian, Jafar; Kolbeinsen, Leiv; Tangstad, Merete (2011-04-02). "Liquidus of Silicon Binary Systems". Metallurgical and Materials Transactions B. Springer Science and Business Media LLC. 42 (4): 852–874. Bibcode:2011MMTB...42..852S. doi: 10.1007/s11663-011-9507-4 . ISSN   1073-5615.
  5. ↑ Galvin, C.O.T.; Grimes, R.W.; Burr, P.A. (2021). "A molecular dynamics method to identify the liquidus and solidus in a binary phase diagram". Computational Materials Science. Elsevier BV. 186: 110016. doi:10.1016/j.commatsci.2020.110016. hdl: 10044/1/82641 . ISSN   0927-0256.
  6. ↑ Deffrennes, Guillaume; Terayama, Kei; Abe, Taichi; Ogamino, Etsuko; Tamura, Ryo (2023). "A framework to predict binary liquidus by combining machine learning and CALPHAD assessments". Materials & Design. Elsevier BV. 232: 112111. doi: 10.1016/j.matdes.2023.112111 . ISSN   0264-1275.
  7. ↑ Miura, Akira; Hokimoto, Tsukasa; Nagao, Masanori; Yanase, Takashi; Shimada, Toshihiro; Tadanaga, Kiyoharu (2017-08-31). "Prediction of Ternary Liquidus Temperatures by Statistical Modeling of Binary and Ternary Ag–Al–Sn–Zn Systems". ACS Omega. American Chemical Society (ACS). 2 (8): 5271–5282. doi: 10.1021/acsomega.7b00784 . ISSN   2470-1343. PMC   6641866 . PMID   31457798.
  8. ↑ Bernhard, Michael; Presoly, Peter; Bernhard, Christian; Hahn, Susanne; Ilie, Sergiu (2021-06-29). "An Assessment of Analytical Liquidus Equations for Fe-C-Si-Mn-Al-P-Alloyed Steels Using DSC/DTA Techniques". Metallurgical and Materials Transactions B. Springer Science and Business Media LLC. 52 (5): 2821–2830. Bibcode:2021MMTB...52.2821B. doi: 10.1007/s11663-021-02251-1 . ISSN   1073-5615.
  9. ↑ Radomski, R.; Radomska, M. (1982). "Determination of solidus and liquidus temperatures by means of a Perkin-Elmer 1B differential scanning calorimeter". Journal of Thermal Analysis. Springer Science and Business Media LLC. 24 (1): 101–109. doi:10.1007/bf01914805. ISSN   0368-4466. S2CID   96845070.
  10. ↑ Sooby, E.S.; Nelson, A.T.; White, J.T.; McIntyre, P.M. (2015). "Measurements of the liquidus surface and solidus transitions of the NaCl–UCl3 and NaCl–UCl3–CeCl3 phase diagrams". Journal of Nuclear Materials. Elsevier BV. 466: 280–285. Bibcode:2015JNuM..466..280S. doi: 10.1016/j.jnucmat.2015.07.050 . ISSN   0022-3115.
  11. ↑ Liu, Gang; Liu, Lin; Zhao, Xinbao; Ge, Bingming; Zhang, Jun; Fu, Hengzhi (2011-03-31). "Effects of Re and Ru on the Solidification Characteristics of Nickel-Base Single-Crystal Superalloys". Metallurgical and Materials Transactions A. Springer Science and Business Media LLC. 42 (9): 2733–2741. Bibcode:2011MMTA...42.2733L. doi:10.1007/s11661-011-0673-4. ISSN   1073-5623. S2CID   135753939.
  12. ↑ Wallenberger, Frederick T.; Smrček, Antonín (2010-05-20). "The Liquidus Temperature; Its Critical Role in Glass Manufacturing". International Journal of Applied Glass Science. Wiley. 1 (2): 151–163. doi:10.1111/j.2041-1294.2010.00015.x. ISSN   2041-1286.
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