Formation regularities of grain-boundary interlayers of the α-Ti phase in binary titanium alloys

Горнакова, А. С.; Prokofiev, S. I.; Kolesnikova, K. I.; Straumal, Boris B.

doi:10.3103/s106782121603007x

Cited by 35 publications

(9 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Some TiFe particles were ordered in chains along the boundaries of the α-Ti grains (see, for example, Figure 1a). This phenomenon is called incomplete or complete grain boundary wetting by a second solid phase and it has been previously observed in various Ti-based alloys [23,[33][34][35][36][37]. In the corresponding SEM/BSE micrographs, the TiFe grains appear to be bright due to a higher Fe content and, thus, a higher mean atomic number of TiFe as compared to α-Ti.…”

Section: Characterization Of the Initial State Of The Samplesmentioning

confidence: 74%

Formation and Thermal Stability of ω-Ti(Fe) in α-Phase-Based Ti(Fe) Alloys

Kriegel

Rudolph

Kilmametov

et al. 2020

Metals

View full text Add to dashboard Cite

In this work, the formation and thermal stability of the ω-Ti(Fe) phase that were produced by the high-pressure torsion (HPT) were studied in two-phase α-Ti + TiFe alloys containing 2 wt.%, 4 wt.% and 10 wt.% iron. The two-phase microstructure was achieved by annealing the alloys at 470 °C for 4000 h and then quenching them in water. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were utilized to characterize the samples. The thermal stability of the ω-Ti(Fe) phase was investigated using differential scanning calorimetry (DSC) and in situ high-temperature XRD. In the HPT process, the high-pressure ω-Ti(Fe) phase mainly formed from α-Ti. It started to decompose by a cascade of exothermic reactions already at temperatures of 130 °C. The decomposition was finished above ~320 °C. Upon further heating, the phase transformation proceeded via the formation of a supersaturated α-Ti(Fe) phase. Finally, the equilibrium phase assemblage was established at high temperatures. The eutectoid temperature and the phase transition temperatures measured in deformed and heat-treated samples are compared for the samples with different iron concentrations and for samples with different phase compositions prior to the HPT process. Thermodynamic calculations were carried out to predict stable and metastable phase assemblages after heat-treatments at low (α-Ti + TiFe) and high temperatures (α-Ti + β-(Ti,Fe), β-(Ti,Fe)).

show abstract

Section: Characterization Of the Initial State Of The Samplesmentioning

confidence: 74%

Formation and Thermal Stability of ω-Ti(Fe) in α-Phase-Based Ti(Fe) Alloys

Kriegel

Rudolph

Kilmametov

et al. 2020

Metals

View full text Add to dashboard Cite

show abstract

“…In polycrystalline materials, equilibrium wetting interlayers of the second phase or second solid phase, which separate grains of the first phase from each other, can form at the temperature of grain boundary wetting phase transformation. Grain boundary phase transformation of wetting by the solid phase have already been observed in several alloys [66,67]. These two phenomena are strongly dependent on the composition of the starting materials as well as the processing temperatures.…”

Section: Brazing Of Titanium Alloys To Aluminamentioning

confidence: 86%

“…The interfaces produced, exhibit complex microstructures: Several distinct layers and/or intermetallic grains completely separated from each other, or for specific conditions, tend to agglomerate. This can be explained by the complete and incomplete wetting of grain boundaries by the liquid [65] or even by a second solid phase [66,67]. It is known that the grain boundary wetting phase transitions can occur in various systems.…”

Section: Brazing Of Titanium Alloys To Aluminamentioning

confidence: 99%

Recent Progress in the Joining of Titanium Alloys to Ceramics

Simões

2018

Metals

View full text Add to dashboard Cite

The prospect of joining titanium alloys to advanced ceramics and producing components with extraordinary and unique properties can expand the range of potential applications. This is extremely attractive in components for the automotive and aerospace industries where combining high temperature resistance, wear resistance and thermal stability with low density materials, good flowability and high oxidation resistance is likely. Therefore, a combination of distinct properties and characteristics that would not be possible through conventional production routes is expected. Due to the differences between the coefficients of thermal expansion (CTE) and Young's modulus of metals and ceramics, the most appropriate methods for such dissimilar bonding are brazing, diffusion bonding, and transient liquid phase (TLP) bonding. For the joining of titanium alloys to ceramics, brazing appears to be the most promising and cost-effective process although diffusion bonding and TLP bonding have clear advantages in the production of reliable joints. However, several challenges must be overcome to successfully produce these dissimilar joints. In this context, the purpose of this review is to point out the same challenges and the most recent advances that have been investigated to produce reliable titanium alloys and ceramic joints. for next-generation aircraft turbine engines [1][2][3][4]. Though, the development of bonding techniques especially to successfully produce dissimilar joints is the key to overcoming the poor room-temperature ductility and fracture toughness of these alloys that limit these potential applications.The possibility of combining the extraordinary properties of these titanium alloys with other materials such as nickel-based superalloys, steel, or even ceramics through dissimilar bonding can allow the development of components not only with complex geometries but also with a combination of properties exceeding the limitations of these materials when used individually.Advanced ceramics have attractive properties, such as high wear resistance, high thermal stability as well as high thermal and electrical conductivities. It is known that some of the advanced ceramics like alumina, silicon nitride, and zirconia, are also well established in the electronics, aerospace, nuclear, and automotive industries [19,20]. However, their inherent brittleness, high cost, and high hardness limit the production of large and complex shape components. The successful application of these advanced ceramics depends strongly on the joining of these materials with metals. In addition, the possibility to combine properties as high wear resistance and high thermal stability with low density, high temperature properties, and excellent creep and corrosion resistance could enable the production of more advanced components that better meet the high requirements of several industrial sectors [21].The most suitable methods for bonding metals and ceramics and producing successful joints with appreciated properties are brazing , diffusion bonding...

show abstract

“…The phase proportion of the MWAAM Ti basic gradient heterogeneous alloy. The precipitation of αS phases is closely related to the complete and incomplete wetting of grain boundary by the second solid phases [34]. The schematic diagram of polycrystals with different wetting angles of the second phase is shown in Fig.…”

Section: Tablementioning

confidence: 99%