Phase Stability Of Ti Research Articles

Neural network interatomic potential-driven analysis of phase stability in Ti–V alloys at the atomistic scale

The evolution of the ω phase in titanium–vanadium (Ti–V) alloys is critical for their mechanical properties, particularly in aerospace and biomedical applications. This study employs a Rapid Artificial Neural Network (RANN) potential to model the ω phase evolution at the atomistic level, demonstrating a high degree of consistency with experimental observations, unlike the Modified Embedded Atom Method (MEAM), which fails to capture this phase transformation accurately. RANN simulations replicate key phenomena such as the nucleation of α precipitates at ω/β interfaces and accurate lattice orientations, enhancing our understanding of phase stability and transformation kinetics. The findings affirm that RANN potentials can significantly improve the prediction accuracy of complex material behaviors, offering a powerful tool for designing advanced materials with tailored properties such as solute effect in various stacking fault energies. This approach not only bridges the gap between theoretical predictions and empirical data but also sets a new direction for future research in materials science, emphasizing the integration of machine learning techniques in the development and optimization of new alloys.

Microstructure and Phase Stability of Ti and Al Co-Added MoSiBTiC Alloys

Microstructure and Phase Stability of Ti and Al Co-Added MoSiBTiC Alloys

The effect of Sn addition on phase stability and phase evolution during aging heat treatment in Ti–Mo alloys employed as biomaterials

Increases in life expectancy and improvements in necessary healthcare attach great importance to the development of biomaterials. Ti alloys containing β stabilizing elements are often used as biomaterials due to their high specific strength, high corrosion resistance, unusual biocompatibility and low elastic moduli, which benefit bone tissues close to an implant. This study deals with phase stability in β Ti–Mo–Sn alloys processed under different conditions and was performed according to the following steps: a study of the effect of Sn content (a) on phase stability in Ti–Mo alloys, (b) on the suppression of α″ and ω phase precipitation; (c) on α-phase precipitation during aging heat treatments and (d) on mechanical properties, including the elastic modulus, as measured using tensile tests and acoustic techniques. The alloys were prepared by arc melting under a controlled atmosphere followed by homogenization heat treatment and hot rolling. Optical microscopy, scanning and transmission electron microscopy, X-ray diffraction and differential scanning calorimetry were employed for characterization purposes. Samples were also submitted to solution treatment above the β transus temperature and aging heat treatments under a controlled atmosphere. The results suggest that Sn suppresses the formation of the ω and α″ phases in Ti–Mo system.

Metal to semiconductor transition and phase stability of Ti1−xMgxNyalloys investigated by first-principles calculations

Titanium nitride based materials are applied in several technological applications owing to their stability at high temperatures, mechanical and optical properties, as well as good electrical conductivity. Here, I use theoretical first-principles methods to investigate the possibilities for a semiconducting state as well as the phase stability of Ti${}_{1\ensuremath{-}x}$Mg${}_{x}$N${}_{y}$ ternary alloys and compounds. I demonstrate that B1 (NaCl) solid solutions of Ti${}_{1\ensuremath{-}x}$Mg${}_{x}$N with $x\ensuremath{\le}0.5$ are thermodynamically stable with respect to all previously reported phases in the Ti-Mg-N system. For the composition $x=0.5$, an ordered TiMgN${}_{2}$ phase with an L1${}_{1}$-type order of Ti and Mg on the metal sublattice is predicted to be the configurational ground state at low temperatures. Other ordered phases present in neighboring materials systems are considered but are found to be unstable. The electronic origin of the stability of the B1 structure solid solutions is identified. A metal to semiconductor transition is observed as the Mg content is increased to $x=0.5$. TiMgN${}_{2}$ as well as disordered Ti${}_{0.5}$Mg${}_{0.5}$N solid solution are investigated with hybrid functional calculations and predicted to be semiconductors with band gaps of 1.1 eV and around 1.3 eV, respectively, the latter depending on the details of the Ti and Mg configuration.

Phase stability of Ti3SiC2 at high pressure and high temperature

Abstract Phase stability of Ti 3 SiC 2 was studied under high pressure and high temperature using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. From the results obtained, the decomposition temperature of Ti 3 SiC 2 decreases quickly against pressure, and the low temperature limits of phase segregation of the sample Ti 3 SiC 2 lie between 1100 °C and 1000 °C, 1000 °C and 900 °C, 900 °C and 800 °C, under high pressures of 3, 4 and 5 GPa, respectively. Ti 3 SiC 2 decomposes to generate TiC, SiC, and TiSi x . On the basis of the experimental results, we suggest two decomposition models to explain the phase decomposition of Ti 3 SiC 2 at high pressure and high temperature.

Influence of impurities on phase stability of martensites in titanium

The influence of H, C, N and O impurities on the phase stability of titanium was studied by first principles total energy calculations. The occupation energies of the impurities were estimated to identify their site preferences. All impurities considered prefer to occupy the octahedral site except for H, which tends to occupy the tetrahedral site in the β phase. Electronic structures were analyzed to clarify the intrinsic influence mechanisms of impurity on the stability of martensitic phases. It was found that the density of states around the Fermi energy, which was affected dramatically by impurity, and the bonding interactions between impurity and titanium were connected to the phase stability of Ti. Elastic constants of impurity-containing systems were estimated from curves of energy against strain to evaluate the mechanical stability of these systems. It was shown that the α″ phase can not be stabilized by impurities considered here, while the α′ phase (regardless of the impurities) and H- and C-containing β phase are thermodynamically stable and also satisfy the mechanical stability criteria.

Tuning phase stability in nanocomposite multilayers

As thin-film layers in a multilayered stack are reduced in thickness, changes in phase stability can result within the individual layers. These changes in phase are expected to have a significant influence upon the functional properties of the nanostructured composite. The ability to engineer, or tune, phase stability at this nanometer length scale is of significant importance in order to maximize the functional properties of these materials. We report the prediction and experimental conformation of tuning the hcp to bcc phase stability in Ti for Ti/Nb multilayered nanocomposites. The prediction was based upon selective alloying of Ti with a bcc β stabilizing element using a new form of a thermodynamic phase diagram for predicting phase stability in thin-film multilayers.

A study of the formation of Ti(CN) solid solutions

The phase stability of Ti(CN) solid solutions was investigated based on the accurate first principles method, the Debye model and the rigid band model beyond a simple ideal mixing model. The Gibbs free energy of formation was calculated using the results from the above models and the standard state energies for the formation of pure TiC and TiN from JANAF tables at varying temperatures. The predicted phases for highest stability at 1700 and 2100 K are in the range of 0.6 and 0.3, whereas those obtained experimentally were near 0.7 and 0.4 nitrogen contents at 1700 and 2100 K, respectively. From the calculation results it can be safely concluded that Ti(CN) solid solutions have higher stability than that predicted by the ideal mixing model.