Evaluation of the high temperature texture of the β phase of a TA6V sample from the individual orientations of grains of the low temperature α phase

1994 ◽  
Vol 30 (3) ◽  
pp. 377-382 ◽  
Author(s):  
M. Humbert ◽  
H. Moustahfid ◽  
F. Wagner ◽  
M.J. Philippe
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Β Phase ◽  
Α Phase ◽  
The Individual

Mechanical Alloying Behavior in the Nb-Si, Ta-Si, and Nb-Ta-Si Systems

1988 ◽  
Vol 133 ◽  
Author(s):  
K. S. Kumar ◽  
S. K. Mannan
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Room Temperature ◽  
Crystalline Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase

ABSTRACTThe mechanical alloying behavior of elemental powders in the Nb-Si, Ta-Si, and Nb-Ta-Si systems was examined via X-ray diffraction. The line compounds NbSi2 and TaSi2 form as crystalline compounds rather than amorphous products, but Nb5Si3 and Ta5Si3, although chemically analogous, respond very differently to mechanical milling. The Ta5Si3 composition goes directly from elemental powders to an amorphous product, whereas Nb5Si3 forms as a crystalline compound. The Nb5Si3 compound consists of both the tetragonal room-temperature α phase (c/a = 1.8) and the tetragonal high-temperature β phase (c/a = 0.5). Substituting increasing amounts of Ta for Nb in Nb5Si3 initially stabilizes the α-Nb5Si3 structure preferentially, and subsequently inhibits the formation of a crystalline compound.

scholarly journals Effects of Double-Ageing Heat Treatments on the Microstructure and Mechanical Behaviour of a Ti-3.5Al-5Mo-4V Alloy

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 209
Author(s):  
Xuanming Ji ◽  
Panpan Ge ◽  
Song Xiang ◽  
Yuanbiao Tan
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Low Temperature ◽  
Mechanical Behaviour ◽  
Ageing Time ◽  
Two Stage ◽  
Ageing Treatment ◽  
Ω Phase ◽  
Α Phase ◽  
Temperature Ageing

In this work, the effect of double-ageing heat treatments on the microstructural evolution and mechanical behaviour of a metastable β-titanium Ti-3.5Al-5Mo-4V alloy is investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The double-ageing treatments are composed of low-temperature pre-ageing and high-temperature ageing, where the low-temperature pre-ageing is conducted at 300 °C or 350 °C for different times, and the high-temperature ageing is conducted at 500 °C for 8 h. The results show that the phase transformation sequence is altered with the time spent during the first ageing stage, the isothermal ω phase is precipitated in the pre-ageing process of the alloy at 300 °C and 350 °C with the change in the ageing time, and the ω phase is finally transformed into the α phase with the extension of pre-ageing time. The existence time of the ω phase is shortened as the pre-ageing temperature increases. The microhardness of the alloy increases with increasing pre-ageing time and temperature. Compared with single-stage ageing, the ω phase formed in the pre-ageing stage changes the response to subsequent high-temperature ageing. After the two-stage ageing treatment, the precipitation size of the α phase is obviously refined after the double-ageing treatment. A microhardness test shows that the microhardness of the two-stage aged alloy increases with extended pre-ageing time.

Constitutive Analysis of the High-Temperature Deformation Behavior of Single Phase α-Ti and α+β Ti-6Al-4V Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 3607-3612 ◽  
Author(s):  
Jeoung Han Kim ◽  
Jong Taek Yeom ◽  
Nho Kwang Park ◽  
Chong Soo Lee
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Deformation Behavior ◽  
Single Phase ◽  
Volume Fraction ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Β Phase ◽  
Α Phase ◽  
Self Consistent

The high-temperature deformation behavior of the single-phase α (Ti-7.0Al-1.5V) and α + β (Ti-6Al-4V) alloy were determined and compared within the framework of self-consistent scheme at various temperature ranges. For this purpose, isothermal hot compression tests were conducted at temperatures between 650°C ~ 950°C to determine the effect of α/β phase volume fraction on average flow stress under hot-working condition. The flow behavior of α phase was estimated from the compression test results of single-phase α alloy whose chemical composition is close to that of α phase of Ti-6Al-4V alloy. On the other hand, the flow stress of β phase in Ti-6Al-4V was predicted by using self-consistent method. The flow stress of α phase was higher than that of β phase above 750°C, while the β phase revealed higher flow stress than α phase at 650°C. Also, at temperature above 750°C, the predicted strain rate of β phase was higher than that of α phase. It was found that the relative strength between α and β phase significantly varied with temperature.

Influences of Solution Temperatures on Microstructure and Mechanical Properties of near α Titanium Alloy

2021 ◽  
Vol 1035 ◽  
pp. 89-95
Author(s):  
Chao Tan ◽  
Zi Yong Chen ◽  
Zhi Lei Xiang ◽  
Xiao Zhao Ma ◽  
Zi An Yang
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
High Temperature ◽  
Room Temperature ◽  
Solution Temperature ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Β Phase ◽  
Α Phase ◽  
New Type

A new type of Ti-Al-Sn-Zr-Mo-Si series high temperature titanium alloy was prepared by a water-cooled copper crucible vacuum induction melting method, and its phase transition point was determined by differential thermal analysis to be Tβ = 1017 °C. The influences of solution temperature on the microstructures and mechanical properties of the as-forged high temperature titanium alloy were studied. XRD results illustrated that the phase composition of the alloy after different heat treatments was mainly α phase and β phase. The microstructures showed that with the increase of the solution temperature, the content of the primary α phase gradually reduced, the β transformation structure increased by degrees, then, the number and size of secondary α phase increased obviously. The tensile results at room temperature (RT) illustrated that as the solution temperature increased, the strength of the alloy gradually increased, and the plasticity decreased slightly. The results of tensile test at 650 °C illustrated that the strength of the alloy enhanced with the increase of solution temperature, the plasticity decreased first and then increased, when the solution temperature increased to 1000 °C, the alloy had the best comprehensive mechanical properties, the tensile strength reached 714.01 MPa and the elongation was 8.48 %. Based on the room temperature and high temperature properties of the alloy, the best heat treatment process is finally determined as: 1000 °C/1 h/AC+650 °C/6 h/AC.

Microstructure Evolution of near α Titanium Alloy during Multi-Step Thermomechanical Deformation Process

2021 ◽  
Vol 1035 ◽  
pp. 305-311
Author(s):  
Qing Shan Liu ◽  
Bo Long Li ◽  
Tong Bo Wang ◽  
Cong Cong Wang ◽  
Peng Qi ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Strain Curve ◽  
Optical Microscope ◽  
Phase Content ◽  
Β Phase ◽  
Α Phase ◽  
Gleeble 3500

A new type of near α high temperature titanium alloy of Ti-Al-Sn-Zr-Mo-Si-Er was studied. The samples with different primary α phase content were prepared by solid solution at 950 °C/1 h—1010 °C/1 h. The multi-step hot compression experiments were carried out by Gleeble-3500 in a sequence of upper region of α + β phase, then followed by lower region of α + β phase. The effects of primary α phase content and deformation temperature on the microstructure of the alloy were studied by means of true stress-strain curve and optical microscope. The results show that the content of primary α phase gradually decreases from 45.4% at 950°C to 0% at 1010°C. As the deformation temperature decreases from 940°C to 900°C, the content of α phase increases gradually from 65% to 94%, which is changed from dynamic recrystallization to deformed structure elongated along RD direction. It is found that the arrangement of α phase along RD direction is the longest at 920°C. With the increase of the deformation temperature in the multi-step high temperature region from 970°C to 990°C, the width of deformed α phase decreases from 3.64 μm at 970°C to 2.71 μm at 990°C. The optimized microstructure is composed of 20% primary α phase arranged along RD direction. This process has a certain potential in the process of hot deformation of the alloy. Key words: high temperature titanium alloy, primary α phase, multi-step hot deformation

Evaluation of Texture Developed in High-Temperature β-Phase during Friction Stir Welding of Ti-6Al-4V

2012 ◽  
Vol 508 ◽  
pp. 106-111 ◽  
Author(s):  
Sergey Mironov ◽  
Yutaka S. Sato ◽  
Hiroyuki Kokawa
Keyword(s):  
High Temperature ◽  
Friction Stir Welding ◽  
Texture Component ◽  
Material Flow ◽  
Fiber Texture ◽  
Shear Texture ◽  
Friction Stir ◽  
Β Phase ◽  
Α Phase ◽  
Pole Figures

The Texture Developed in High-Temperature β Phase during Friction Stir Welding of Ti-6Al-4V Was Studied. It Was Demonstrated that 0002 and 1120 Pole Figures Calculated from α Phase May Be Employed for Interpretation of Material Flow in the β Phase. Together with Orientation Measurements in Retained β Phase, this Approach Was Shown to Be a Very Simple and Effective for the Texture Analysis. The β Texture Was Found to Be a Mixture of {hkl}<111>-Fiber Texture and D2(112)[111](Simple-Shear Texture Component.

A Molecular Dynamics Study on Pressure Dependence of Ag Diffusion in Ag3SI

2010 ◽  
Vol 72 ◽  
pp. 337-342
Author(s):  
Masakazu Yarimitsu ◽  
Masaru Aniya
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
High Temperature ◽  
Pressure Dependence ◽  
Distribution Functions ◽  
Intermediate Temperature ◽  
Β Phase ◽  
Α Phase ◽  
Method Of Molecular Dynamics ◽  
Pair Distribution Functions

The pressure dependence of the diffusion coefficient in the superionic α- and β-phases of Ag3SI has been studied by using the method of molecular dynamics. It is shown that in the high temperature α-phase, the Ag diffusion coefficient decreases with pressure. On the hand, in the intermediate temperature β-phase, the Ag diffusion coefficient exhibits a maximum at around 2.8 GPa. The structural origin of this behavior is discussed through the pressure dependence of the pair distribution functions.

scholarly journals Phase transition and structures of the twinned low-temperature phases of (Et4N)[ReS4]

2020 ◽  
Vol 76 (3) ◽  
pp. 231-235
Author(s):  
Eduard Bernhardt ◽  
Regine Herbst-Irmer
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Title Compound ◽  
Room Temperature ◽  
Monoclinic Space Group ◽  
Rapid Cooling ◽  
Space Group ◽  
Disordered Structure ◽  
Β Phase ◽  
Α Phase

The title compound, tetraethylammonium tetrathiorhenate, [(C2H5)4N][ReS4], has, at room temperature, a disordered structure in the space group P63 mc (Z = 2, α-phase). A phase transition to the monoclinic space group P21 (Z = 2, γ-phase) at 285 K leads to a pseudo-merohedral twin. The high deviation from the hexagonal metric causes split reflections. However, the different orientations could not be separated, but were integrated using a large integration box. Rapid cooling to 110–170 K produces a metastable β-phase (P63, Z = 18) in addition to the γ-phase. All crystals of the β-phase are contaminated with the γ-phase. Additionally, the crystals of the β-phase are merohedrally twinned. In contrast to the α-phase, the β- and γ-phases do not show disorder.

scholarly journals Effect of Heat treatment on Microstructure and Mechanical Properties of Ti-6Al-2Zr-1Mo-1V Bar

2020 ◽  
Vol 321 ◽  
pp. 11046
Author(s):  
Xu Enen ◽  
Tian Yanwen ◽  
Hao Fang ◽  
Cu Linin ◽  
Du Yuxuan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
High Temperature ◽  
Microstructure Evolution ◽  
Second Stage ◽  
Β Phase ◽  
Α Phase ◽  
Duration Time ◽  
Stage Heat Treatment

In this paper, the microstructure evolution and mechanical properties fluctuation of Ti-6Al-2Zr-1Mo-1V forging state bar after the first stage heat treatment at 950℃~955℃ and the second stage heat treatment at 760℃~840℃ were studied. In the first stage of heat treatment, the content of primary α and the tensile strength decreases with the increase of temperature, and the high temperature duration time is obviously prolonged. During the second stage of heat treatment, the metastable β phase precipitates third α phase, and with the increase of temperature, the tensile strength increases and the high temperature duration time prolongs.

Crystal structure of the high-pressure monoclinic phase-II of cristobalite, SiO2

2000 ◽  
Vol 64 (3) ◽  
pp. 569-576 ◽  
Author(s):  
M. T. Dove ◽  
M. S. Craig ◽  
D. A. Keen ◽  
W. G. Marshall ◽  
S. A. T. Redfern ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Neutron Diffraction ◽  
Phase Ii ◽  
Monoclinic Phase ◽  
Β Phase ◽  
Α Phase ◽  
Temperature And Pressure ◽  
Pressure Phase

AbstractThe crystal structure of the high-pressure phase-II of cristobalite has been solved by neutron diffraction (space group P21/c, a = 8.3780(11) Å, b = 4.6018(6) Å, c = 9.0568(13) Å, β = 124.949(7)°, at P = 3.5 GPa). This phase corresponds to a distortion of the high-temperature cubic β-phase, rather than of the ambient temperature and pressure tetragonal α-phase.

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