volume change of iron from bcc to fcc

The Body-Centered Cubic (BCC) unit cell can be imagined as a cube with an atom on each corner, and an atom in the cube's center. Does the volume increase or decrease when FCC changes to BCC iron? Research Article. But above 910C, iron is called -iron with FCC crystal structure. At this transition, the heat capacity of Fe has a characteristic -shape form with a maximum at TC9,10. Learn more about Stack Overflow the company, and our products. Phys. If you stretch a piece of copper that its length doubles and its radius shrinks by the ratio of two, what is the ration of resistance changes? b. decreases. Differentiating eq. But in between them, rotated by $45^\circ$, is the unit cell of the bcc lattice, stretched along the $z$ axis. The flux through a closed surface surrounding the sock is 17 kNm^2/C. Tectonophys. At 11851667K the crystal structure of iron changes to a face-centred cubic (fcc) cell (-Fe or fcc-Fe), however, above 1667K and up to the melting temperature of 1811K, iron again has the bcc structure (-Fe). At 30 GPa, the dhcp phase appears in the diffraction patterns. Answer in Mechanical Engineering for MASOOD HANIF KASU #173485 Thus, the problem of consistent EoSs for solid phases (bcc-Fe, fcc-Fe, and hcp-Fe) and liquid iron remains extremely important. A gain of 6 dB means that the signal level or strength: a. increases very little. View the full answer. PDF USNA :: United States Naval Academy Strong size effect on deformation twin-mediated plasticity in body High Press. Calculate the volume change associated with the change in crystal structure. When heated, it transforms from BCC to FCC at 1185 K. The atomic radii of iron atoms at this temperature are 0.126 and 0.129 nm for bcc and fcc, respectively. & Prakapenka, V. In-situ X-ray diffraction measurements of the - transition boundary of iron in an internally-heated diamond anvil cell. a-e transition pathway of iron under quasihydrostatic pressure conditions. & Bell, P. Calibration of the ruby pressure gauge to 800 kbar under quasi-hydrostatic conditions. At higher pressures, the room temperature isotherm6 is consistent with our EoS of hcp-Fe (Supplementary Figure S8). 3.7 Iron has a BCC crystal structure, an atomic radius of 0.124 nm, and an atomic weight of 55.85 g/mol. Phys. At 10.5GPa and 753K7 (or by more precise and recent measurements at 8.2GPa and 678K11), there is a triple point between bcc-Fe, fcc-Fe, and the high-pressure phase hcp-Fe, which has the hexagonal close-packed (hcp) structure (hcp-Fe). B., Ahuja, R. & Johansson, B. Quasi - Ab initio molecular dynamic study of Fe melting. See Page 1. The best answers are voted up and rise to the top, Not the answer you're looking for? Hope you'll find our explanations and tips useful! Res. High pressure effects on the ironiron oxide and nickelnickel oxide oxygen fugacity buffers. J. Statist. B 91, 174105 (2015). Chem. The extrapolation of this line from the low-pressure data (Fig. Thus, it . reviewed the manuscript. 99, 42734284 (1994). Using the hard sphere model, which imagines each atom as a discrete sphere, the BCC crystal has each atom touch along the body diagonal of the cube. Science Lett. Google Scholar. In this work, the volume and pressure effects on thermodynamic quantities including Gruneisen parameter and melting temperature of sodium have been studied of to 65 GPa. Sodium has bcc packing. Molodets, A. Thermodynamic potentials and non-monotonic melting curve of sodium at high pressure. Calculate the percent change in density from BCC to FCC. C. 4. Only few available interatomic interaction potentials implement the phase transformation in iron by featuring a stable low-temperature bcc and high-temperature fcc lattice structure. The authors6 used a third-order BirchMurnaghan EoS to fit the parameters on the room temperature isotherm with a fixed initial density 0=8.2695gcm3 and obtained K0=172.7GPa and K0=4.79. ADS At the transformation temperature the lattice parameter of BCC iron is 28 . The authors used a microscopic phenomenological model for longitudinal spin fluctuations (LSFs) based on density functional theory calculations. Inter. & Dewaele, A. Equations of state of MgO, Au, Pt, NaCl-B1, and NaCl-B2: Internally consistent high-temperature pressure scales. W is the prototype for BCC. Solution-Manual-for-Physical-Metallurgy-Principles-4th-Edition-by The adiabatic bulk modulus for liquid Fe is about 3.04.5% lower than the PREM and the calculated95 KS is 3.19.0% higher than the PREM (Fig. Recently, thermodynamic functions for fcc, hcp, and liquid iron were tabulated20. At high pressure and temperature, iron was found to be paramagnetic47. Lost your password? Lithium, sodium, potassium, vanadium, chromium, iron, rubidium, niobium, molybdenum, cesium, barium, europium, tantalum and tungsten all have the BCC crystal structure. How many atoms belong to the BCC cell? A cylindrical copper rod has resistance R. It is reformed to twice its original length with no change of volume. Nature 427, 339342 (2004). B 79, 060101 (2009). Elements in the same period on the Periodic Table will have the.. A. the same number of electrons B. same number of protons C. an increasing number of protons as they move across the period D. decreasing number of protons as they mov. [19], The exact temperatures at which iron will transition from one crystal structure to another depends on how much and what type of other elements are dissolved in the iron. [10][11] The maximum solubility of carbon is about 0.02 wt% at 727C (1,341F) and 0.001% at 0C (32F). SciEngMat Enhanced 7e SI Ch14 PowerPoint | PDF | Ductility | Alloy At these conditions, the entropy for liquid iron, S=114.15Jmol1K1 and hcp-Fe, S=107.2Jmol1K1, were determined from eqs 7 and 17. Ruban, A. V., Belonoshko, A. Phase diagram of iron: Implications for the state of the Earths core. I r. [20], "Gamma loop" redirects here. 0.1292 nm respectively. Stability field of the hcp-structure for Fe, Fe-Ni, and Fe-Ni-Si alloys up to 3 Mbar. arXiv:cond-mat/0207318v1 [cond-mat.mtrl-sci] 12 Jul 2002 It is one of the most common structures for metals. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Zarkevich, N. A. BCC metals have a ductile-to-brittle transformation temperature (DBTT), which means that they are brittle at lower temperatures and ductile at higher temperatures. B) increases. Equation of state of pure iron and Fe0.9Ni0.1 alloy up to 3 Mbar. 91, 46734676 (1986). To calculate the pressure, the Ne, NaCl-B2, and Pt pressure scales52, and the MgO pressure scale71 were used. J. Phys. So, some BCC metals are ductile at room temperature, and others are brittle. Saxena, S. K. & Eriksson, G. Thermodynamics of iron at extreme pressures and temperatures. This can be made clear by figure 6. . Let the switch be closed at t = 0. What is the percentage volume change upon transformation from bcc to fcc? Tectonophys. It was argued that hcp-Fe is likely a stable phase in the inner core of the Earth12,13,14. True or false: The value of the RC time constant decreases when C decreases. The phase diagram of Fe is relatively complex due to the existence of several polymorphic modifications7,8. 3 mol liter-1 in 5 seconds. Combustion, Explosion, and Shock Waves 50, 582598 (2014). BCC also has 12 tetrahedral sites, which means that a small interstitial atom could fit in 12 positions such that it is equally surrounded by 4 FCC lattice atoms. Slip systems determine many mechanical properties of materials, and is the main reason why a material will be ductile or brittle. However, under the Earths core conditions (P 360GPa, T 6000K) Fe acquires a substantial local magnetic moment47, up to 1.3B. =88GPa and =2800K17 or =98.5GPa and =3712K14). Many metals such as iron, chromium, tungsten, molybdenum, and vanadium have the BCC crystal structure at room temperature. For fcc crystals the atoms of iron are on the cube corners and at the centres of each face of the cube. Dorogokupets P. I., Sokolova T. S., Dymshits A. M. & Litasov K. D. Thermodynamic properties of rock-forming oxides, -Al2O3, Cr2O3, -Fe2O3, and Fe3O4 at high temperatures and pressures. Show that the reciprocal lattice of a direct BCC lattice is an FCC lattice. Figure 5a shows the calculated isentropic temperature profile started from ICB conditions for liquid iron. Is iron a bcc or FCC? - Heimduo A square is cut out of a copper sheet. Differentiation of the thermal pressure with respect to temperature at constant volume gives the pressure slope at constant volume: The volume dependence of and q was accepted in the Altshuler form44: The volume dependence of the Einstein temperature can be expressed as: In eqs (12,13,14,15) 0 is the Grneisen parameter at reference conditions, is the Grneisen parameter at infinite compression (x=0), and is a fitted parameter. Phase Equilibria 3, 161165 (1982). Styling contours by colour and by line thickness in QGIS. Show that the FCC structure is denser than the BCC structure. The square is heated uniformly, as a result, it turns into a) a square with larger area. The + phase field is, technically, the + field above the A2. Geophys. 2.6 m/s^2 to km/hr^2 c. 3.5 m^2. Mao, H., Wu, Y., Chen, L., Shu, J. The beta designation maintains continuity of the Greek-letter progression of phases in iron and steel: -Fe, -Fe, austenite (-Fe), high-temperature -Fe, and high-pressure hexaferrum (-Fe). Res. PubMed Central Iron melting curve with a tricritical point. CAS Science Lett. Institute of Earths Crust, SB RAS, Irkutsk, Russia, V. S. Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk, Russia, Novosibirsk State University, Novosibirsk, Russia, You can also search for this author in 119, 41644177 (2014). 2). FCC. BCC and HCP Metals - University of Rhode Island 26, 206211 (1999). There are two triple points along the melting line of Fe. FCC unit cell has 4 atoms per unit cell as compared to BCC having 2 atoms per unit cell. In any crystal structure, there are small holes in between the usual atoms into which smaller interstitial atoms may sit to form interstitial solid solution. Report No. This result is consistent with the data from the shock wave experiments93,94. After the passage of 140 amperes for 482.5 sec, the mass of anode decreased by 22.260 g and the cathode increased in mass by 22.011. & Ponyatovsky, E. G. In Advances in Metallic Alloys V.4 Phase transformations of elements under high pressure (eds Fridlyander, J. N. & Eskin, D. G. ) 377 (CRC Press Boca Raton, Florida, 2005). If you increase the multiplicity by a factor of 10, how much does the scaled entropy, S/k, change? Iron fe undergoes an allotropic transformation at 912 375, 244253 (2013). The EoSs of the liquid and solid iron phases were constrained based on the Helmholtz free energy. High-pressurehigh-temperature equation of state of KCl and KBr. Phys. Look for this article in the future on our website! ADS Changes in the Properties of Iron during BCC-FCC Phase Transition Accompanying this transformation is a change in the atomic radius of Fefrom rBCC= 0.12584 nm to rFCC = 0.12894 nmand, in addition a change in density (and volume). The high-pressure phases of iron are important as models for the solid parts of planetary cores. Face-Centered Orthorhombic11. The metastable line bcchcp-iron was also calculated at high pressures. The pressure calculated based on these parameters is 3GPa higher than that obtained by our EoS at 50150GPa. Pure iron goes through a polymorphic change from BCC to FCC upon heating at 912C. The formalism for the magnetic contribution to the Helmholtz free energy was adapted from ref. B. In our model (eq. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. J. Geophys. The calculated triple points at the phase diagram have the following parameters: bccfcchcp is located at 7.3GPa and 820K, bccfccliquid at 5.2GPa and 1998K, and fcchcpliquid at 106.5GPa and 3787K. At conditions near the fcchcpliquid triple point, the Clapeyron slope of the fccliquid curve is dT/dP=12.8K/GPa while the slope of the hcpliquid curve is higher (dT/dP=13.7K/GPa). Rev. Phys. c. It is unchanged. J. Geophys. Number of atoms . 0.725C. Rev. 2-At 912 C, iron changes from the BCC (-Fe) to the FCC (-Fe) structure. (c) increases by 2. If the copper is replaced with aluminum, how thick will the aluminum slab have to be to reduce the rate of gamma-rays by the same amount as the copper slab? The diffusion coefficient of carbon FCC iron is lower than BCC iron because a) the temperature is higher for FCC b) FCC has a higher packing factor c) FCC is more cubic d) Carbon is substitional i For greater pressures, published data (as of 2007) put the --liquid triple point at pressures that differ by tens of gigapascals and 1000K in the melting point. BCC (as-deposited) to BCC+FCC (a fluence of 6 10 19 ion/cm 2) to BCC 1 (a fluence of 1.8 10 21 ions/cm 2) [4]. Slider with three articles shown per slide. The radius in BCC is R B C C = 0.12584 R_{BCC}=0.12584 R BCC = 0.12584 and that for FCC is R F C C = 0.12894 R_{FCC}=0.12894 R FCC = 0.12894. 95, 2173721742 (1990). Nature 363, 534536 (1993). Calphad 2, 227238 (1978). The newly measured melting line of Fe extrapolated to 330GPa reveals a temperature of about 6230500 K14. Iron (Fe) undergoes an allotropic transformation at 912 C: upon heating from a BCC (phase) to an FCC ( phase). The packing fraction is the ratio of volume taken by actual atoms and the total volume of the cube. Caijuan Shi, Oliver L. G. Alderman, Chris J. Benmore, Akihiko Machida, Hiroyuki Saitoh, Katsutoshi Aoki, Andrew J. Schultz, Sabry G. Moustafa & David A. Kofke, Koutaro Hikosaka, Shoh Tagawa, Yasuo Ohishi, Konstantin D. Litasov, Tatyana B. Bekker, Konstantin E. Kuper, Scientific Reports At higher pressures, the fcc phase is in the stability field of the liquid. a.) The melting curve of iron to 250 gigapascals: A constraint on the temperature at Earths center. 6 are in reasonable agreement with our EoS of hcp-Fe. If I_0 is 92 mR/h, the HVL for an isotope is 0.47 cm, and the thickness of the shield is 1.51 cm, what will be the intensity after the beam has passed through the shield? The ratio of density of the crystal before heating and after heating is [atomic weight of F e =56 ]A. Geophys. 27, 431446 (2007). A student kept his 9.0 V, 5.6 W radio turned on at full volume from 4.00 P.M. until 3.00 A.M. Rubidium forms the positive Rb+. The obtained EoSs allow calculation of PVT relations and thermodynamic properties of Fe at the Earths core conditions (up to 6000K and 350GPa). At this temperature, the atomic radii of the iron atom in the two structures are 0.1258 nm and. Correspondence to a. 3.6 g/cm^3 to kg/m^3 b. Trying to understand how to get this basic Fourier Series. Data 15, 967983 (1986). P.D., T.S., A.D. and K.L. ADS However, the more scattered data62 deviate by 2 to +4GPa at 298K isotherm and significantly overestimate pressures at high temperatures. Science 236, 181182 (1987). A. 6. BCC is nearly close-packed and has an APF of 0.68. The calculated triple points at the phase diagram have the following parameters: bcc-fcc-hcp is located at 7.3 GPa and 820 K, bcc-fcc-liquid at 5.2 GPa and 1998 K, and fcc-hcp-liquid . Zeitschrift fur Angewandte Physik 23, 245249 (1967). Res. & Tatsumi, Y. 77 is located at a higher temperature than most determined triple points (Fig. a. Earth Planet. Res. Base-Centered Monoclinic14. The authors declare no competing financial interests. S. I. Novikova, Thermal Expansion of Solids (Nauka, Moscow, 1974 . Inter. 8 7 4 g c m 3. B 87, 014405 (2013). Chem. By submitting a comment you agree to abide by our Terms and Community Guidelines. Many of its properties arise because the next-nearest neighbors bond nearly as powerfully as the nearest neighbors. 1. Sola, E. & Alfe, D. Melting of Iron under Earths Core Conditions from Diffusion Monte Carlo Free Energy Calculations. (d) Calculated P-wave velocity along the isentrope. Volume Change During BCC to FCC Iron transformation - YouTube Melting of compressed iron by monitoring atomic dynamics. Rev. Comparisons of other thermodynamic functions, which are second derivatives of the Gibbs energy or the Helmholtz free energy, are not necessary. Strong size effect on deformation twin-mediated plasticity in body-centered-cubic iron. Miner. When you increase r by a factor of 3, 1 r^2 will by a factor of . Diamond Tetragonal (White Tin)8. 95, 2173121736 (1990). (choose either increase, decrease, or no change) Strength _____ Ductility _____ Elastic modulus _____, If 1.5 x 10^{14} boron atoms per cm^3 are added to silicon as a substitutional impurity, determine what fraction of the silicon atoms are displaced in the lattice. & Guyot, F. Thermal equation of state of iron and Fe0.91Si0.09. The body-centred position is empty. We've added a "Necessary cookies only" option to the cookie consent popup, FCC lattice as a stack of triangular lattices, Understanding FCC and BCC Bravais Lattices, Structure Factor for a Simple BCC Lattice. 55, 56 and 60 using the NaCl scale60, a better consistency with our EoS for bcc-Fe is obtained, which confirms the relevance of the experimental data mentioned above55,56. J. Its new resistance is equal to 2R. Below 912C (1,674F), iron has a body-centered cubic (bcc) crystal structure and is known as -iron or ferrite. Iron has a BCC structure at room temperature. By what percent is the radius of 239 92 U greater than the radius of 232 92 U? J. Geophys. If the magnetic moment for hcp-Fe is 0=0.04 and TN=67K (see eqs 19,20,21), then the hcpliquid curve shifts to higher temperatures (red squares on Fig. FCC-to-BCC phase transition in NaCl, Buckingham or Lennard-Jones potentials? Soln. Round your result to 2 decimal places. Let's consider only one unit cell for the calculation of percentage change in the density and volume. Res. Google Scholar. You can see that, if the fcc cell dimensions are taken to be of unit length, the body-centred tetragonal cell has dimensions $\frac{1}{\sqrt{2}}\times \frac{1}{\sqrt{2}} \times 1$. 84). Different structures are different as they have different arrangements of atoms in the lattice. PDF Effect of Alloying Elements on the - Phase Transformation in Iron The following transition can be caused by the kinetics of the transition process or the effect of fcc-Fe and hcp-Fe magnetic moment. Komabayashi, T., Fei, Y., Meng, Y. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. If I_0 is 95 mR/h, the HVL for an isotope is 0.42 cm, and the thickness of the shield is 1.39 cm, what will be the intensity after the beam has passed through the shield? The atomic mass of Fe is 55.845 gr/mol. Most of the ab initio estimations provide higher melting temperatures of Fe at 330 GPa compared with our data: 6700600K87, 6370100K88, 6900400K89, 71007200K90, 6325K91, and 6345K92. Make sure to explain clearly the different steps you have undertaken to come up with the solution. Calphad 29, 6889 (2005). The segregation effects of Co and Cr on the bcc Fe 3 [1 1 0] (1 1 1) grain boundary cohesion are investigated based on the Rice-Wang thermodynamics model by the first-principles DMol method within the framework of density functional theory. The phase boundary between the different solid phases is drawn on a binary phase diagram, usually plotted as temperature versus percent iron. Mechanical metamaterials made of freestanding quasi-BCC nanolattices of In a body-centered cubic crystal, each atom has 8 nearest neighbors (NN). Given Parameter in Lattice parameter of BCC = Side of cenit cell of a Bec iron - abce = 2 . If you are interested in why BCC metals have different properties than FCC metals (another common structure), you should check out this article. 37, 677684 (2010). Boehler, R. The phase diagram of iron to 430 kbar. Answer (1 of 3): It's the thermodynamics of these two crystal structures. In any fission process, the ratio: (a) Equal to 1 (b) Greater than 1 (c) Less than 1 (d) Depends on the mass of the parent nucleus. (Definition, Examples, and Metallurgy), The Difference Between Alloys and Composites (and Compounds), The Hume-Rothery Rules for Solid Solution. 38, 272276 (1967). Note that the radius of the largest nucl, A 0.840 \ m long brass pendulum experiences a 21.0^oC temperature increase. The calculated melting lines of iron from the bcc, fcc, and hcp phases are shown in Figs 1, 2 and 3. In these works, various pressure scales were used based on the EoSs of Au, MgO, NaCl, KCl, and hcp-Fe. During a particular thunderstorm, the electric potential difference between a cloud is V_{cloud}-V_{ground}=3.20 \times 10^8 V, with the cloud being at the higher potential. a. twice as much b. three times as much c. approximately 4.8 times as much d. six, A photocopy machine can reduce copies to 80% of their original size. We applied the new EoS data for all Fe phases to calculate the phase diagram up to 350GPa (Figs 1, 2 and 3). How does the number of atoms in a 27.5-gram iron ring compare to the number in a chrome ring of the same mass? B. inversely proportional. & Huang, H. Thermal equation of state of hcp-iron: Constraint on the density deficit of Earths solid inner core. Why does iron have a bcc and FCC structure? - ProfoundAdvice This question is of materials in civil engineering and needs to be Brown, M. J. Mechanical Engineering. 56, 172189 (2015). Their triple point liquid is located at 81GPa and 3200K and at 330GPa the melting line is located at 5400K. Another estimation indicates a melting temperature of 6100K at 330GPa21. It is thermodynamically stable and a fairly soft metal. The susceptibility of annealed iron at saturation is 5500. The amount of -Fe depends on the cooling process. Miner. (Crystal Structure, Properties, Interstitial Sites, and Examples), What is the Difference Between FCC and HCP? Google Scholar. Calculate the volume change ?V/V (%) arising from the transformation of iron from FCC to BCC during cooling from 1000 C. What is the respective length change ?L/L? Finally, the melting line of Fe measured using a synchrotron-based fast X-ray diffraction method was also proposed14. 014101 (2014). Sakai, T. et al. Lett. Most measurements are scattered for less than 2GPa in the 80GPa pressure range (Supplementary Figure S7). 93, 091904 (2008). Find the length of the side of the original square. Desai, P. D. Thermodynamic properties of iron and silicon. 42, 32393244 (1973). In elements that reduce the gamma phase range, the alpha-gamma phase boundary connects with the gamma-delta phase boundary, forming what is usually called the Gamma loop. 1.069B. That means that the body diagonal has a length of , which works out to that the lattice parameter , or side length of the cube, has a length of . 45 to obtain the correct limit of entropy at 0K. The magnetic contribution to the Helmholtz free energy can be expressed as45: where B0 is an average magnetic moment per atom, =T/T*, T* is the critical temperature (TC for ferromagnetic materials and Neel temperature TN for paramagnetic materials). Iron (Fe) undergoes an allotropic transformation from a BCC to FCC structure system. Not to be confused with, Experimental high temperature and pressure, "The magnetic state of the phase of iron", https://en.wikipedia.org/w/index.php?title=Allotropes_of_iron&oldid=1137712070, This page was last edited on 6 February 2023, at 01:58. Explore what a crystal lattice is, various types of crystal lattice structures and the concept of translational symmetry. Geophys. (5) at T f = 1184 K: the upper curve is for bcc-Fe; the lower curve is for fcc-Fe. 49 corrected based on pressure scales31,35. At moderate and high pressures, such extrapolation provides reliable results with a close agreement with reference data20. Almost all properties . The density of iron is 7. M. N. Magomedov. Being about twice the diameter of the tetrahedral hole, the carbon introduces a strong local strain field. What happens to the field if the number of turns is doubled, with the length remaining the same? It is important to compare the thermodynamics of these phases calculated by different methods. However, it was shown that at 18GPa bcc-Fe transforms into hcp-Fe and the value of the magnetic moment becomes zero46. 14. We determined the density deficit of hcp-Fe at the inner core boundary (T=5882K and P=328.9GPa) to be 4.4%. Dziewonski, A. M. & Anderson, D. L. Preliminary reference Earth model. It is stable up to its melting point of 1,538C (2,800F). Rev. BCC is nearly close-packed and has great stability because of its high number of nearest neighbors and next-nearest neighbors. Miner. Altshuler, L. V., Brusnikin, S. E. & Kuzmenkov, E. A. Isotherms and Gruneisen functions for 25 metals. If you calculate the energy of the BCC and fcc structures of iron, you will find that the FCC has a significantly lower than the BCC variant at room temperature. Conductor A has nine times the diameter and nine times the length of conductor B. (a) Calculate the volume change associated with the change in crystal structure from BCC to FCC if at 912C the BCC unit cell had a lattice constant a = 0.293 nm and the FCC unit cell a lattice constant a=0.363 nm. Jamieson, J. C., Fritz, J. N. & Manghnani, M. H. In High Pressure Research in Geophysics Pressure measurement at high temperature in X-ray diffraction studies: gold as a primary standard (eds Akimoto, S. & Manghnani, M. H. ) 2748 (Center for Academic Publications, Tokyo, 1982). This inconsistency is probably due to the differences in the EoSs. Thermodynamics and Equations of State of Iron to 350GPa and 6000K. Get the most important science stories of the day, free in your inbox. 92, 93199325 (1987). (With Examples Beyond Carbon). & Bi, W. Sound velocities of bcc-Fe and Fe0.85Si0.15 alloy at high pressure and temperature. Metallic iron changes from BCC to FCC form at 9100C. This phenomenon is called the ductile-to-brittle transformation temperature (DBTT).