Phase Transformations of the Ti-40% Nb Alloy Under External Influence

2016 ◽  
Vol 683 ◽  
pp. 174-180 ◽  
Author(s):  
Yuri P. Sharkeev ◽  
Zhanna G. Kovalevskaya ◽  
Margarita A. Khimich ◽  
Vladimir A. Bataev ◽  
Qi Fang Zhu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Phase Transformation ◽  
Severe Plastic Deformation ◽  
Phase Transformations ◽  
Optical Metallography ◽  
External Influence ◽  
Β Phase ◽  
Α Phase ◽  
Pressing Operation ◽  
Loading Axis

The phase transformations of the alloy Ti-40 mas % Nb after tempering and severe plastic deformation are studied. The phase transformations of the alloy according to the type and conditions of external influences are analyzed using methods of XRD, SEM and optical metallography. It is determined that inverse phase transformation of the metastable α''-phase to equilibrium β-phase is carried out after severe plastic deformation. Complete phase transformation α'' → β is typical for the mode, which consists of three pressing operation with the change of the loading axis in cramped conditions, followed by a multi-pass rolling in grooved rolls.

scholarly journals The Phase Transformations Induced by High-Pressure Torsion in Ti–Nb-Based Alloys

2021 ◽  
pp. 1-7
Author(s):  
Anna Korneva ◽  
Boris Straumal ◽  
Askar Kilmametov ◽  
Lidia Lityńska-Dobrzyńska ◽  
Robert Chulist ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Chemical Compositions ◽  
Β Phase ◽  
Ω Phase ◽  
Α Phase ◽  
Nb Content ◽  
Long Time

The study of the fundamentals of the α → ω and β → ω phase transformations induced by high-pressure torsion (HPT) in Ti–Nb-based alloys is presented in the current work. Prior to HPT, three alloys with 5, 10, and 20 wt% of Nb were annealed in the temperature range of 700–540°C in order to obtain the (α + β)-phase state with a different amount of the β-phase. The samples were annealed for a long time in order to reach equilibrium Nb content in the α-solid solution. Scanning electron microscope (SEM), transmission electron microscopy, and X-ray diffraction techniques were used for the characterization of the microstructure evolution and phase transformations. HPT results in a strong grain refinement of the microstructure, a partial transformation of the α-phase into the ω-phase, and a complete β → ω phase transformation. Two kinds of the ω-phase with different chemical compositions were observed after HPT. The first one was formed from the β-phase, enriched in Nb, and the second one from the almost Nb-pure α-phase. It was found that the α → ω phase transformation depends on the Nb content in the initial α-Ti phase. The less the amount of Nb in the α-phase, the more the amount of the α-phase is transformed into the ω-phase.

Effect of Strain Amounts on Cold Compression Deformation Mechanism of Ti-55531 Alloy with Bimodal Microstructure

2021 ◽  
Vol 1035 ◽  
pp. 182-188
Author(s):  
Jian Hua Cai ◽  
She Wei Xin ◽  
Lei Li ◽  
Lei Zou ◽  
Hai Ying Yang ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Deformation Mechanism ◽  
True Strain ◽  
Bimodal Microstructure ◽  
Free Zone ◽  
Β Phase ◽  
Α Phase ◽  
Initial Stage ◽  
Pile Up ◽  
Dislocation Tangle

The plastic deformation mechanism of Ti-55531 alloy with bimodal microstructure was investigated by compression testing at room temperature. The bimodal microstructure was composed of equiaxed primary α phase (αp) and transformed β (βtrans) that consisted of acicular secondary α phase (αs) and residual β phase (βr). In the initial stage of deformation, the αp grains first underwent plastic deformation, the dislocations germinated and increased, forming the dislocation loop with the dislocation free zone in αp at the true stain of 0.083. With the true strain subsequently increasing to 0.105, the dislocation tangle and dislocation pile-up occurred in αp, and a lot of dislocations were also activated in most of αs. Moreover, the dislocation density was increasing gradually in βr with the adding of strain. Finally, the dislocation pile-up and dislocation tangle appeared in αs and βr at the true strain of 0.163. The whole deformation process was coordinated by αp, αs and βr. They accommodated mutually and completed deformation together.

Evidence of Bulk Nanostructuring in Zr-Based Alloys under Deformation at Temperatures of α↔β Phase Transformations

2010 ◽  
Vol 667-669 ◽  
pp. 629-634
Author(s):  
Margarita Isaenkova ◽  
Yuriy Perlovich ◽  
Vladimir Fesenko ◽  
Olga Krymskaya ◽  
Alexander Zavodchikov
Keyword(s):  
Plastic Deformation ◽  
Phase Transformations ◽  
Texture Features ◽  
X Ray ◽  
Β Phase ◽  
Crystallographic Slip ◽  
Interphase Boundaries ◽  
Grain Fragmentation ◽  
Temperature Rate ◽  
Zr Alloys

The deformation behavior of commercial Zr alloys with 1% and 2,5%Nb under compression at temperatures of the (α+β)-region of Zr-Nb phase diagram is considered on the basis of experimental data obtained by X-ray texture study of deformed samples. Mechanisms, responsible for plastic deformation of alloys by different temperature-rate regimes were determined on the basis of resulting textures. Among these mechanisms there are crystallographic slip and mutual displacements of crystallites along interphase boundaries. The latter mechanism sharply intensifies by grain fragmentation down to nanostructuring under conditions of α«β phase transformations. Texture features of deformed samples testify about interaction of plastic deformation with phase transformations and indicate that due to this interaction compression by optimal regimes promotes the utmost refinement of structure elements.

β-Phase Stability of Two Biomedical β-Titanium Alloys During Severe Plastic Deformation

JOM ◽  
2020 ◽  
Vol 72 (8) ◽  
pp. 2937-2948
Author(s):  
Doina Raducanu ◽  
Vasile Danut Cojocaru ◽  
Anna Nocivin ◽  
Ion Cinca ◽  
Nicolae Serban ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Titanium Alloys ◽  
Phase Stability ◽  
Β Phase

Phase Transformation Cycle β→ α′ + α + α"→ β in Ti6Al4V Alloy

2015 ◽  
Vol 828-829 ◽  
pp. 232-238 ◽  
Author(s):  
Kalenda Mutombo ◽  
Siyasiya Charles ◽  
Waldo Stumpf
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Phase Field ◽  
Xrd Analysis ◽  
External Stress ◽  
Ti6al4v Alloy ◽  
Β Phase ◽  
Α Phase ◽  
Sequential Transformation ◽  
Dsc Thermograms

The β-phase transforms to α′, α and α" within a range of temperature from the β-transus (Tβ) to about 600°C, considering no external stress is applied. Two types of microstructure were obtained: acicular martensite when rapidly cooled and lamellar α/β when slowly cooled from the β phase field. The sequential transformation of β into α′, α-phase, α2, and α" was revealed as peaks on the coefficient thermal expansion (CTE) curves, however, reversed transformations: α"→β, and α→β, were revealed by the DSC thermograms. The presence of β, α′, α, α2 and α" was identified by means of XRD analysis and HRTEM.

Enhancing the stability of β phase in TiZr via severe plastic deformation

2013 ◽  
Vol 588 ◽  
pp. 416-419 ◽  
Author(s):  
Zhibo Zhang ◽  
Ming Li ◽  
Defeng Guo ◽  
Yindong Shi ◽  
Tengyun Ma ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Β Phase ◽  
The Stability

X-ray study of the twinning and phase transformation of phosphocristobalite (AlPO4)

1977 ◽  
Vol 55 (7-8) ◽  
pp. 677-683 ◽  
Author(s):  
H. N. Ng ◽  
C. Calvo
Keyword(s):  
Phase Transformation ◽  
Transition Temperature ◽  
Short Range ◽  
X Ray ◽  
First Order ◽  
Β Phase ◽  
Α Phase ◽  
Short Range Correlations

Crystals of the cristobalite polymorph of AlPO4 (phosphocristobalite) up to 3 mm in breadth were grown from a V2O5 flux. In the α phase (C2221), the presence of twin domains prevents an accurate resolution of the structure as a function of temperature. The six twin components of this phase readily lead to a disordered β phase [Formula: see text] with short range correlations as suggested previously. The α–β transformation is first order with a substantial hysteresis in the transition temperature.

Sign in / Sign up

Export Citation Format

Share Document