Liquidus Projection Research Articles

Investigation of Mechanical and Corrosion Properties of New Mg-Zn-Ga Amorphous Alloys for Biomedical Applications.

Magnesium alloys are considered as promising materials for use as biodegradable implants due to their biocompatibility and similarity to human bone properties. However, their high corrosion rate in bodily fluids limits their use. To address this issue, amorphization can be used to inhibit microgalvanic corrosion and increase corrosion resistance. The Mg-Zn-Ga metallic glass system was investigated in this study, which shows potential for improving the corrosion resistance of magnesium alloys for biodegradable implants. According to clinical tests, it has been demonstrated that Ga ions are effective in the regeneration of bone tissue. The microstructure, phase composition, and phase transition temperatures of sixteen Mg-Zn-Ga alloys were analyzed. In addition, a liquidus projection of the Mg-Zn-Ga system was constructed and validated through the thermodynamic calculations based on the CALPHAD-type database. Furthermore, amorphous ribbons were prepared by rapid solidification of the melt for prospective alloys. XRD and DSC analysis indicate that the alloys with the most potential possess an amorphous structure. The ribbons exhibit an ultimate tensile strength of up to 524 MPa and a low corrosion rate of 0.1-0.3 mm/year in Hanks' solution. Therefore, it appears that Mg-Zn-Ga metallic glass alloys could be suitable for biodegradable applications.

Thermodynamic Modeling of the Au-Ge-X (X = In, Sb, Si, Zn) Ternary Systems.

In this study, the CALPHAD approach was employed to model the thermodynamics of the Au-Ge-X (X = In, Sb, Si, Zn) ternary systems, leveraging experimental phase equilibria data and previous assessments of related binary subsystems. The solution phases were modeled as substitutional solutions, and their excess Gibbs energies were expressed using the Redlich-Kister polynomial. Owing to the unavailability of experimental data, the solubility of the third elements in the Au-In, Au-Sb, and Au-Zn binary intermetallic compounds was excluded from consideration. Additionally, stable ternary intermetallic compounds were not reported in the literature and, thus, were not taken into account in the present thermodynamic calculations. Calculations of liquidus projections, isothermal sections, and vertical sections for these ternary systems have been performed, aligning with existing experimental findings. These thermodynamic parameters form a vital basis for creating a comprehensive thermodynamic database for Au-Ge-based alloys, which is essential for the design and development of new high-temperature Pb-free solders.

Solidified microstructure and phase equilibria of the Cu–Cr–X (X=Mg, Y) ternary systems

The Cu–Cr alloys with magnesium and yttrium exhibit appealing high-strength and high-conductivity (HSHC) characteristics. Anticipated contributions to the design of HSHC copper alloys include new insights from understanding the phase equilibria, solidified microstructure, and thermodynamics of the Cu–Cr–X (X = Mg, Y) systems. Five Cu–Cr–Y alloys and three Cu–Cr–Mg alloys were melted through arc melting and powder metallurgy, respectively. An analysis was conducted on the primary phases and solidification path of the as-cast Cu–Cr–Y alloys. Five three-phase regions in the Cu–Cr–Y system and three in the Cu–Cr–Mg system at the isothermal sections of 673 K were identified using XRD and EPMA. No ternary compound was discovered among either of these systems. The agreement between the experimental data and the calculated isothermal sections and liquidus projection derived from the thermodynamic description of the binary systems is quite good. The investigation on phase equilibria in Cu–Cr–X (X = Mg, Y) systems in this study helps in developing the thermodynamic database for multi-component copper alloys.

Phase equilibria in the Al–Fe–Mo system

This paper presents the results of our comprehensive study of phase equilibria in the Al–Fe–Mo system using DTA, X-ray diffraction, SEM and electron probe microanalysis. The liquidus and solidus projections were constructed. It is shown that the ternary compound Al8FeMo3 (τ) melts congruently at >1500 °C and has a homogeneity range from 2 to 9 at.% Fe and from 23.5 to 25 at.% Mo. Isostructural phases (Mo), (αFe) and AlMo (W-type structure, cI2-Im-3m) at solidus temperatures form a continuous solid solution (αFe,Mo,AlMo). Unlike the AlMo binary phase, which is not retained by quenching, the ternary (αFe,Mo,AlMo) phase is easily quenched due to its lower decomposition temperature. Among the binary based phases, the Al8Fe5 (ε) phase has the widest homogeneity region, which extends up to 24 at.% Mo at solidus temperatures. It is shown that the addition of Mo stabilizes the Al8Fe5 (ε) phase, and the temperature of its formation in the ternary system increases to 1331 °C in contrast to 1234 °C in the binary. Moreover, according to XRD data, the Al8Fe5 (ε) phase in the ternary system has a rhombohedral structure of the Al8Cr5-type (hR78-R-3m), rather than cubic Cu5Zn8-type structure (cI52-I-43m), like the binary one. A new binary compound Al45Mo7 was identified for the first time. Its crystal structure is established as monoclinic Al45V7-type (mS104-C2/m) with the lattice parameters a = 20.534, b = 7.561, c = 10.910 Å, β = 107.33. It was shown to form by peritectic reaction L + Al5Mo ⇄ Al45Mo7 at ∼800 °C. Iron additions stabilize the Al4Mo phase, which in the binary system is stable above 942 °C.

Phase equilibria and solidification behavior of Mg–Al–Gd casting alloys

The Mg–Al–Gd ternary system was re-assessed by the CALPHAD (CALculation of PHAse Diagrams) method and a set of self-consistent thermodynamic parameters of the system were obtained. The long-period stacking ordered (LPSO) phases, 14H and 18R, were described by thermodynamic model of Mgx(TM,Mg)6(RE,Mg)8 (TM=Transition Metal, RE=Rare Earth). Representative isothermal sections, vertical sections, liquidus projections and the related invariant reactions were calculated and compared with the experimental data, showing the reliability of the obtained thermodynamic parameters. Reaction scheme for the whole ternary system was also presented. The Scheil solidification paths and the phase fractions of several Mg–Al–Gd alloys were calculated and analyzed. The phase formation during solidification and the phase content of γ and LPSO phases are clearly described with the increase of Gd content, which is crucial to the microhardness, ultimate tensile strength and yield strength of Mg–Al–Gd casting alloys.

Experimental investigation and CALPHAD modeling of the Mo-Nb-Zr system

To accelerate the design of novel nuclear fuel cladding materials for applications, the phase equilibria of the Mo-Nb-Zr system at 1223 K and 1773 K have been experimentally investigated by a combination of scanning electron microscopy, energy dispersive spectroscopy, electron probe microanalysis with wavelength dispersive spectrometer. In addition, the liquidus of the vertical sections at x(Mo) + x(Nb) = 0.67, x(Zr) + x(Nb) = 0.60 were also studied in this work utilizing an in-situ high-speed pyrometer. The thermodynamic assessment of the Mo-Nb-Zr system was carried out by the CALPHAD method based on the experimental data available in the present work and literature. A set of self-consistent thermodynamic parameters of the Mo-Nb-Zr system was obtained. The calculated liquidus projection of the Mo-Nb-Zr system over the whole composition was also presented.

Formation and characterization of Al10CaFe2 compound in Al−Ca−Fe alloys

The phase diagram of the Al−Ca−Fe system in the aluminum corner, including the liquidus projection and solidification reactions, was studied by using thermodynamic calculations and experimental techniques. The results show that instead of the Al3Fe phase, a ternary compound whose composition corresponds to the formula Al10CaFe2 should be in equilibrium with the aluminum solid solution (Al). Thе transition from the binary to the ternary compound occurs via the peritectic transformation L + Al3Fe → (Al) + Al10CaFe2 (at 638 °C, 3.3 at.% Ca and 0.5 at.% Fe). Primary and eutectic crystals of the ternary compound have a compact morphology, in contrast to needle-shaped inclusions of the Al3Fe phase. First principles calculations and X-ray diffraction analysis were used to determine the crystal lattice structure of Al10CaFe2 ternary compound. In addition, the near eutectic alloy Al−6wt.%Ca−1wt.%Fe after annealing at 500−600 °C has a fine structure with a total fraction of excess phases of about 25 vol.%. Thus, the Al−Ca−Fe system can be used to create new aluminum-matrix composite alloys.

Experimental investigation and thermodynamic assessment of phase equilibria in the Al–Cr–Ta ternary system

The Al–Cr–Ta ternary system was investigated through a combination of experiments and thermodynamic modeling. The determination of the liquidus projection involved the microstructural characterization of 29 as-cast alloys using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Sublattice models were proposed for the phases according to their crystal structures and homogeneity ranges. Based on the experimental results, the Al–Cr–Ta ternary system was thermodynamically assessed by the CALculation of PHase Diagrams (CALPHAD) approach. The liquidus projection, isothermal sections, and vertical sections of the ternary system were calculated. A set of self-consistent thermodynamic parameters for the Al–Cr–Ta ternary system was obtained with a satisfactory agreement between the experimental and calculated results. The present work could be significant for the practical application of novel cemented carbides and future thermodynamics assessment of complex multicomponent systems.

Experimental investigation of the CaO-Al2O3-TiO2 system: Isothermal section of 1500 °C and liquidus projection

The CaO-Al2O3-TiO2 phase diagram is of great guiding significance for the comprehensive utilization of Ti-bearing mineral resources and the design of metallurgical slag for Al-Ti alloy steel. In this paper, the high-temperature phase equilibrium experimental method was adopted; the types and compositions of phases were identified by Electron Probe Micro Analysis (EPMA) and X-ray diffraction (XRD). A total of 12 equilibrium phases were determined, including CaO, Al2O3, TiO2, 3CaO2TiO2, 4CaO3TiO2, CaOTiO2, Al2O3TiO2, 3CaOAl2O3, CaOAl2O3, CaO2Al2O3, CaO6Al2O3, and Liquid; they formed a total of 16 phase equilibrium relations. The isothermal section of CaO-Al2O3-TiO2 system at 1500 °C in atmosphere was constructed for the first time. There are 10 three-phase fields (Liquid+CaO+3CaO2TiO2, Liquid+3CaO2TiO2+4CaO3TiO2, CaOTiO2+CaOAl2O3+CaO2Al2O3, CaO2Al2O3+CaOTiO2+CaO6Al2O3, Liquid+CaOTiO2+ CaO6Al2O3, Liquid+CaO6Al2O3+Al2O3, Liquid+Al2O3+Al2O3TiO2, Liquid+TiO2+Al2O3TiO2, Liquid+CaOAl2O3+4CaO3TiO2, 4CaO3TiO2(ss)+CaOTiO2(ss)+CaOAl2O3), 13 two-phase fields (Liquid+CaO, CaO+3CaO2TiO2, Liquid+3CaO2TiO2, Liquid+4CaO3TiO2, Liquid+TiO2, Liquid+CaOTiO2, Liquid+Al2O3TiO2, Liquid+Al2O3, Liquid+CaO6Al2O3, Liquid+CaOAl2O3, CaOTiO2(ss)+CaO2Al2O3, 4CaO3TiO2(ss)+CaOTiO2(ss), 4CaO3TiO2(ss)+3CaO2TiO2(ss)), 2 single-phase solid solution fields (4CaO3TiO2(ss), 3CaO2TiO2(ss)), and 2 disconnected single liquid phase fields. On this basis, the liquidus projection of the CaO-Al2O3-TiO2 system was revised. The types of relevant invariant reactions were identified by the Lever Rule; the types of relevant univariant reactions were determined by the original method proposed in this paper.

Experimental investigation and thermodynamic assessment of the Na2O–Al2O3–CaO system

Thermodynamic investigation of the Na2O–Al2O3–CaO system plays an important role in the applications of HACs and refractory. However, the phase relationships in the Al2O3-rich corner of the isothermal section at 1473 K for this system are uncertain. Key experimental investigation was performed and an improved method was developed to prepare the samples. Four three-phase regions of NC3A8+CA2+β-Al2O3, CA2+CA6+β-Al2O3, CA6+β-Al2O3+Al2O3 and NC3A8+NA6+β-Al2O3 were confirmed by X-ray diffraction. The Na2O–Al2O3 system was reassessed by CALPHAD method and the Na2O–Al2O3–CaO system was optimized by using the ionic two-sublattice liquid model (Na+1,Al+3,Ca+2)P(AlO2−1,O−2)Q to describe the liquid phase and a sublattice compound energy formalism model (Na+1)2(Ca+2,Na+1)1(Al+3)4(O−2)8(Va,Na+1)1 to describe the ternary compound NCA2. A set of self-consistent thermodynamic parameters was finally obtained, satisfactorily reproducing the experimental data and predicting the liquidus projection and primary phase regions. The present thermodynamic investigation of the Na2O–Al2O3–CaO system contributes to compositional design in HACs and refractory.

Phase relationships at 1673 K and thermodynamic evaluation of ZrO2–SrO–CaO system

Twelve samples of the ZrO2–SrO–CaO system were prepared, quenched from 1673 K to room temperature, and characterized by XRD and SEM/EDS methods to investigate the phase relations of the ZrO2–SrO–CaO system at 1673 K. The results showed that four solid solution phases exist: (Sr, Ca)ZrO3, (Sr, Ca)2ZrO4, (Sr, Ca)3Zr2O7 and (Sr, Ca)4Zr3O10. Based on the experiments as well as the literature data, the ZrO2–SrO–CaO system was evaluated by the CALPHAD (CALculation of PHAse Diagram) method, and the isothermal sections at 1673 K and 2073 K and a liquidus projection were calculated. The calculation results were in good agreement with most of experimental results, which proves that the database is self-consistent and reliable, and this work can be applied to the design of novel refractories.

Thermodynamic assessment of the Cr–Mo–Si ternary system

Based on the experimental isothermal sections at 1000 and 1200 °C and the liquidus projection from the measurements by the present authors, the Cr–Mo–Si ternary system is thermodynamically assessed using the CALculation of PHAse Diagram method (CALPHAD). The parameters of the thermodynamic descriptions of all the phases in the Cr–Mo–Si ternary system are optimized on the basis of the reported thermodynamic data and the constitution models of the Cr–Mo, the Cr–Si and the Mo–Si terminal binary systems. Two solution phases, liquid and bcc_A2, were described as substitutional solutions. The intermetallic phases, CrSi, CrSi2 and MoSi2, were modeled by two sublattices, (Cr,Mo):Si, (Cr,Mo):Si2 and (Mo,Cr):Si2, respectively, while βCr5Si3 was modeled by three sublattices (Cr,Mo,Si)2:(Cr,Si)3:Cr3. Cr3Si and Mo3Si have the same crystal structure (cP8, Pm-3n) and present a continuous intermetallic phase M3Si with the two sublattice model (Cr,Mo,Si)3:(Cr,Si)1. Similarly, αCr5Si3 and Mo5Si3 with the same crystal structure (tI32, I4/mcm) form a continuous intermetallic phase M5Si3 with the three sublattice model (Cr,Mo)4:(Cr,Mo,Si)1:(Mo,Si)3. Since the very small solubilities of Cr and Mo, the Diamond-Si phase was treated as a pure element phase. Using the current optimized parameters, the isothermal sections, the liquidus projection and the reaction sequence chart are calculated. The comparison between the calculated results and the experimental investigations, including the isothermal sections, the liquidus projection, and the solidification processes of the as cast alloys, shows that the present calculation can well reproduce the experimental equilibria. The present modeling can finely describe the experimental information of the Cr–Mo–Si ternary system.

Phase Equilibria of the V-Ti-Fe System and Its Applications in the Design of Novel Hydrogen Permeable Alloys.

The precise liquidus projection of the V-Ti-Fe system are crucial for designing high-performance hydrogen permeation alloys, but there are still many controversies in the research of this system. To this end, this article first uses the CALPHAD (CALculation of PHAse Diagrams) method to reconstruct the alloy phase diagram and compares and analyses existing experimental data, confirming that the newly constructed phase diagram in this article has good reliability and accuracy. Second, this obtained phase diagram was applied to the subsequent development process of hydrogen permeation alloys, and the (Ti65Fe35)100-xVx (x = 0, 2.5, 5, 10, 15, 25) alloys with dual-phase {bcc-(V, Ti) + TiFe} structure were successfully explored. In particular, the alloys with x values equal to 2.5 at.% and 5 at.% exhibit relatively high hydrogen permeability. Third, to further increase the H2 flux permeation through the alloys, a 500-mm-long tubular (Ti65Fe35)95V5 membrane for hydrogen permeation was prepared for the first time. Hydrogen permeation testing showed that this membrane had a very high H2 flux (4.06 mL min-1), which is ca. 6.7 times greater than the plate-like counterpart (0.61 mL min-1) under the same test conditions. This work not only indicates the reliability of the obtained V-Ti-Fe phase diagram in developing new hydrogen permeation alloys, but also demonstrates that preparing tubular membranes is one of the most important means of improving H2 flux.

Phase Equilibria, Solidified Microstructure, and Hydrogen Transport Behaviour in the V-Ti-Co System.

At present, the V-Ti-Co phase diagram is not established, which seriously hinders the subsequent development of this potential hydrogen permeation alloy system. To this end, this article constructed the first phase diagram of the V-Ti-Co system by using the CALculation of PHAse Diagrams (CALPHAD) approach as well as relevant validation experiments. On this basis, hydrogen-permeable VxTi50Co50-x (x = 17.5, 20.5, …, 32.5) alloys were designed, and their microstructure characteristics and hydrogen transport behaviour were further studied by XRD, SEM, EDS, and so on. It was found that six ternary invariant reactions are located in the liquidus projection, and the phase diagram is divided into eight phase regions by their connecting lines. Among them, some alloys in the TiCo phase region were proven to be promising candidate materials for hydrogen permeation. Typically, VxTi50Co50-x (x = 17.5-23.5) alloys, which consist of the primary TiCo and the eutectic {bcc-(V, Ti) and TiCo} structure, show a high hydrogen permeability without hydrogen embrittlement. In particular, V23.5Ti50Co26.5 exhibit the highest permeability of 4.05 × 10-8 mol H2 m-1s-1Pa-0.5, which is the highest value known heretofore in the V-Ti-Co system. The high permeability of these alloys is due in large part to the simultaneous increment of hydrogen solubility and diffusivity, and is closely related to the composition of hydrogen permeable alloys, especially the Ti content in the (V, Ti) phase. The permeability of this alloy system is much higher than those of Nb-TiCo and/or Nb-TiNi alloys.

Experimental determination and thermodynamic calculation of phase equilibria in Ag-Zr-Y system

The phase equilibria of the Ag-Zr-Y system at 800, 600 and 500 °C were investigated by means of X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersive X-ray spectrometry (EDS) techniques. The solubilities of Y in the Ag2Zr and AgZr phases and of Zr in the Ag51Y14, Ag2Y and AgY phases were measured, and no ternary compound was found in these isothermal sections. By means of the CALPHAD method, thermodynamic parameters of the Ag-Zr-Y system were assessed based on the experimental data from the present work and the literature. Substitutional solution model was used to describe the solution phases and sublattice models were used to describe binary compounds. A set of self-consistent and accurately described thermodynamic parameters of the Ag-Zr-Y system were obtained. The representative isothermal sections and liquidus projection were calculated, and the Hill reaction scheme of the Ag-Zr-Y system was constructed. The calculated results are in agreement with the experimental data.

An experimental investigation of phase transformations in the Al-Fe-V system

This paper presents a comprehensive study of phase equilibria in the Al-Fe-V system by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA) and electron probe microanalysis (EPMA). Liquidus and solidus projections, a number of isothermal and vertical sections, as well as a reaction scheme (Scheil diagram) are constructed. On the solidus surface, there is a continuous solid solution Al8(Fe,V)5 (Cu5Zn8-type structure, cI52-I-43 m), which decomposes with decreasing temperature. The limited solid solution formed in this case has the widest homogeneity region. At 1000 and 700 °C, the solubility of iron in it is 25 and 18 at.% Fe, respectively. The solidus surface is characterized by six three-phase fields: (Al) + Al13Fe4 + Al45V7, (Al) + Al21V2 + Al45V7, Al3V + Al23V4 + Al45V7, Al3V + Al45V7 + Al13Fe4, Al8(Fe,V)5 + Al3V + Al13Fe4 and Al8(Fe,V)5 + Al13Fe4 + Al5Fe2, which result from invariant four-phase equilibria. One of them is of the peritectic type, the others are of transition type. Equilibria take place at 653, ∼660, 735, 755, 1086, and 1121 °C, respectively. In the two-phase area AlFe + Al8(Fe,V)5 the solidus surface has a temperature minimum at 1188 °C, resulting from the invariant eutectic three-phase equilibrium L ⇄ AlFe + Al8(Fe,V)5. At ∼1080 and 730 °C, solid-state invariant four-phase equilibria Al8V5 + Al2Fe ⇄ AlFe + Al5Fe2 and Al8V5 + Al5Fe2⇄ AlFe + Al13Fe4, respectively, occur.

Thermodynamic modeling of B–Mo–Nb ternary system with modified B–Nb description

Based on a critical evaluation of the literature data, the B–Mo–Nb ternary system has been assessed by means of the CALPHAD (CALculation of PHAse Diagrams) technique. There is no ternary compound reported in this system. According to their crystal structures, the substitutional solution is adopted to model the ternary liquid, and the sublattice models are used to describe the Mo2B, αMoB, (Mo,Nb)B, (Mo,Nb)B2, Mo2B5, MoB4, Nb3B2, Nb5B6, Nb3B4, Nb2B3, (Mo,Nb) and (B) phases. The modeling covers the whole composition and temperature ranges. Due to the same crystal structure, the sublattice model of the NbB phase in the B–Nb binary system is adjusted as (Me,Va)0.5(B,Va)0.5, in order to be consistent with the βMoB phase in the B–Mo binary system. The obtained thermodynamic parameters of the B–Mo–Nb system are demonstrated to be self-consistent and reasonable by adequately comparing the calculated and reported thermodynamic information and phase diagram. Based on the present thermodynamic parameters, the liquidus projection and reaction scheme of B–Mo–Nb system are presented.

Phase equilibria in the Zr-Co-Sn system

Phase equilibria upon crystallization in the Zr-Co-Sn system were experimentally studied by a combination of scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and differential thermal analysis (DTA). The liquidus projection, melting diagram (liquidus + solidus), vertical sections, Scheil reaction scheme, and isothermal sections at 1000 and 1200 °C covering the whole concentration range were constructed. Four ternary intermetallic phases ZrCo2Sn (τ1), ZrCoSn (τ2), Zr6Co1.65Sn1.35 (τ3) and Zr5Co6Sn18 (τ4) are confirmed. It is shown that ZrCo2Sn (τ1) and ZrCoSn (τ2) melt congruently at 1470 and 1340 °C, respectively, while Zr6Co1.65Sn1.35 (τ3) and Zr5Co6Sn18 (τ4) form by peritectic reactions L + Zr5Sn3+x ⇄ τ3 and L + τ1 + τ2 ⇄ τ3 at 1270 and 1130 °C, respectively. The binary phases Zr5Sn3+x and ZrCo2 (Laves phase) have extended homogeneity ranges in the ternary system. A total of twenty-four four-phase invariant reactions are established: one peritectic, six eutectic, one eutectoid and sixteen U-type.

Experimental investigation and thermodynamic modeling of the Cr–Zr–Si system

The phase equilibria of the Cr–Zr–Si ternary system were studied combined with the key experiments and thermodynamic assessment. Thirty-five ternary alloys were prepared to determine the isothermal sections at 900 and 1000 °C by means of X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS). Five ternary compounds, i.e., τ1 (CrSi2Zr), τ2 (Cr4Si5Zr2), τ3 (Cr4Si7Zr4), τ4 (CrSiZr) and τ5 (Cr3SiZr2), were confirmed. The solubilities of the third element in binary compounds were determined. Based on the experimental phase equilibria data available in the present work and the literature, as well as the thermodynamic parameters of constitutive binary systems, the Cr–Zr–Si system was evaluated by using the CALPHAD (CALculation of PHAse Diagram) method. A set of self-consistent thermodynamic parameters was obtained. Three isothermal sections and liquidus projection were calculated and the reaction scheme was constructed. The calculated results are in agreement with the experimental data.

The MgO–TiO2–SiO2 system: Experiments and thermodynamic assessment

AbstractPhase relations in the MgO–TiO2–SiO2 system have been investigated in air over a wide temperature range using the equilibration method. X‐ray powder diffraction, scanning electron microscopy combined with wave length X‐ray spectroscopy (SEM/EPMA), and differential thermal analysis (DTA) have been used for sample characterization. Based on the obtained experimental results, isothermal sections of the system at 1523, 1673, and 1773 K have been established. The solid‐state invariant reaction MgTi2O5 + T‐SiO2⇋P‐MgSiO3 + TiO2 has been detected at 1625 ± 8 K by step‐wise heat treatment. A partial liquidus projection has been suggested, and the temperatures and compositions of three eutectic invariant reactions have been experimentally measured by DTA and ex‐situ analysis of the sample microstructures after melting using SEM/EPMA. Considering the newly obtained experimental data, thermodynamic parameters describing the system have been thermodynamically evaluated within the CALPHAD approach.