RE-Boronizing below Beta Transus Temperature on TC4 Titanium Alloy Surface

2013 ◽  
Vol 750-752 ◽  
pp. 651-654 ◽  
Author(s):  
Jin Sheng Li ◽  
Feng Hua Li ◽  
Li Lei ◽  
Xiao Hong Yi ◽  
Zhan Guo Fan ◽  
...  
Keyword(s):  
Rare Earth Oxide ◽  
Boride Layer ◽  
Work Piece ◽  
Hardness Profile ◽  
Beta Transus ◽  
Duplex Microstructure ◽  
Tc4 Titanium Alloy ◽  
Β Phase ◽  
Transus Temperature ◽  
Lower Temperature

Ti6Al4V (TC4) slices were boronized with rare earth oxide (RE) addition in the agent at 950°C (below β phase transus of TC4). The morphology, phases, properties and structures of TC4 matrix and boride layers were studied. The results show that the boride layer on the surface of TC4 consists of TiB2 and TiB dual compounds. The boride layer is compact, uniform and less porous compared with that obtained at 1050°C (above β phase transus of TC4), and the hardness profile and brittleness of the layers are improved to a certain extent. Lower temperature boronizing can effectively prevent the growth of coarse β phase grains. Duplex microstructure is obtained in TC4 matrix, and the work piece distortion is reduced.

Electropulsing-Induced α to β Phase Transformation of Ti–6Al–4V

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jihui Huang ◽  
Zhutian Xu ◽  
Yujun Deng ◽  
Linfa Peng
Keyword(s):  
Phase Transformation ◽  
Transformation Process ◽  
Transformation Rate ◽  
Avrami Model ◽  
Β Phase ◽  
Specific Effects ◽  
Heating Treatment ◽  
Transus Temperature ◽  
Lower Temperature ◽  
Electropulsing Treatment

Abstract Electrically assisted forming (EAF) has been increasingly utilized as an effective auxiliary processing technology to improve the formability of hard-to-deform metals. Previous works have revealed that the phase transformation of titanium alloys subjected to electropulsing treatment (EPT) can occur at a lower temperature and in a remarkably shorter time compared with those subjected to the traditional heating treatment (THT). However, an in-depth experimental verification and further analysis is still missing so far. Therefore, to characterize the specific effects of EPT on α → β transformation process, both EPT and THT experiments were conducted on Ti–6Al–4V sheet specimens. After that, a calculation method based on the analysis of optical microscopic (OM) metallographs was developed to characterize the amount of phase transformation in EPT and THT. According to the results, it was found that the pulse current can significantly reduce the phase transus temperature and accelerate the transformation process in EPT compared with that in THT. Furthermore, the specific effects of EPT on transus temperature and phase transformation rate were investigated in detail. Based on that, the transformation kinetics of the electropulsing-induced α → β phase transformation was also analyzed using the Johnson–Mehl–Avrami model. It is revealed that the activation energies of both nucleation and growth of phase transformation are reduced by electric current. Hence, the phase transformation can start at a lower temperature and with a higher rate in EPT. The mechanism behind the effects was also discussed in detail in the present work.

scholarly journals Dynamic Softening Mechanisms and Microstructure Evolution of TB18 Titanium Alloy during Uniaxial Hot Deformation

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 789
Author(s):  
Qiang Fu ◽  
Wuhua Yuan ◽  
Wei Xiang
Keyword(s):  
Titanium Alloy ◽  
Dynamic Recovery ◽  
True Strain ◽  
Hot Workability ◽  
Compression Tests ◽  
Phase Zone ◽  
Β Phase ◽  
Stability And Instability ◽  
Dynamic Softening ◽  
Transus Temperature

In this study, isothermal compression tests of TB18 titanium alloy were conducted using a Gleeble 3800 thermomechanical simulator for temperatures ranging from 650 to 880 °C and strain rates ranging from 0.001 to 10 s−1, with a constant height reduction of 60%, to investigate the dynamic softening mechanisms and hot workability of TB18 alloy. The results showed that the flow stress significantly decreased with an increasing deformation temperature and decreasing strain rate, which was affected by the competition between work hardening and dynamic softening. The hyperbolic sine Arrhenius-type constitutive equation was established, and the deformation activation energy was calculated to be 303.91 kJ·mol−1 in the (α + β) phase zone and 212.813 kJ·mol−1 in the β phase zone. The processing map constructed at a true strain of 0.9 exhibited stability and instability regions under the tested deformation conditions. The microstructure characteristics demonstrated that in the stability region, the dominant restoration and flow-softening mechanisms were the dynamic recovery of β phase and dynamic globularization of α grains below transus temperature, as well as the dynamic recovery and continuous dynamic recrystallization of β grains above transus temperature. In the instability region, the dynamic softening mechanism was flow localization in the form of a shear band and a deformation band caused by adiabatic heating.

Microstructural Study of Newly Designed Ti-6Al-1Fe Alloy through Deformation

2017 ◽  
Vol 264 ◽  
pp. 54-57
Author(s):  
Ayad Omran Abdalla ◽  
Astuty Amrin ◽  
Roslina Mohammad ◽  
M.A. Azmah Hanim
Keyword(s):  
Titanium Alloy ◽  
Cold Rolling ◽  
Hot Rolling ◽  
Lamellar Microstructure ◽  
Ti Alloy ◽  
Beta Transus ◽  
Complete Replacement ◽  
Microstructural Study ◽  
Equiaxed Microstructure ◽  
Transus Temperature

Recently, iron (Fe) is introduced to substitute vanadium (V) in Ti-alloy. Therefore, new (α+β) titanium alloy, Ti-6Al-1Fe was designed through a complete replacement of V by Fe with major composition modifications of Ti-6Al-4V. This new alloy is believed could provide similar properties of Ti-6Al-4V through modification of its microstructures. Different heat treatments can lead to a diversity of microstructural permutations and combinations. Thus, it is very crucial to study in-depth understanding about the microstructure of Ti-6Al-1Fe. Results reveal that the microstructure of as-received alloy is a typical fine lamellar microstructure. The bi-modal microstructure can be obtained by hot rolling below beta-transus temperature (Tβ) followed by recrystallization treatment at 925°C. While cold rolling followed by recrystallization treatment at 925°C produce equiaxed microstructure.

Influence of Aging Temperature on Microstructure and Creep Properties of Hot Continuous Rolled Ti-6Al-4V Alloy

2012 ◽  
Vol 560-561 ◽  
pp. 943-946
Author(s):  
Li Xiao ◽  
Su Gui Tian ◽  
Xian Yu Bao
Keyword(s):  
Strain Rate ◽  
Aging Temperature ◽  
Creep Property ◽  
Solution Treatment ◽  
Continuous Rolling ◽  
Β Phase ◽  
Industrial Manufacture ◽  
Hot Continuous Rolling ◽  
New Processing ◽  
Lower Temperature

Hot continuous rolling technique is a new processing method for preparing Titanium alloy, which may decrease the production cost and realize continuous industrial manufacture. Ti-6Al-4V alloy was prepared by hot continuous rolling (HCR) and solution and aging treated at different temperature. Creep curves of the alloys were measured, microstructure evolution feature of the alloys during creep was observed by SEM and TEM. The influence of aging temperature on the microstructure and creep property of the alloy is briefly discussed. Results show that, the microstructure of HCR alloy after solution treatment at temperature higher than β phase transus point consists of the fully "basket weave" structure. The alloy aged at 750 °C has higher strain rate and shorter creep lifetime, strain rate of the alloy during steady-state creep is measured to be 0.69 × 10-7/s, creep lifetime is measured to be 180h, and strain rate of the alloy aged at 480 °C is measured to be 0.33 × 10-7/s. The alloy aged at lower temperature has longer creep lifetime than the alloy aged at high temperature.

Thermal Evolution and Electrical Properties of Rare-Earth Oxide Doped Zirconia

1988 ◽  
Vol 121 ◽  
Author(s):  
B. S. Chiou ◽  
M. Y. Lee ◽  
J. G. Duh
Keyword(s):  
Activation Energy ◽  
Rare Earth ◽  
Ionic Radius ◽  
Thermal Evolution ◽  
Rare Earth Oxide ◽  
Zirconia Ceramics ◽  
Wet Chemical ◽  
Ir Analysis ◽  
Lower Temperature ◽  
The Rare Earth

ABSTRACTSynthesized zirconia ceramics are prepared through the coprecipita-tion process. Application of the wet chemical approach is aimed at the achievement of highly sintered ceramics at lower temperature. The thermal evolution of the synthesized CeO2-ZrO2 powder is investigated with the aid of DTA and TGA measurement. The exothermic peaks on the DTA thermogram are futher identified by the IR analysis. The effect of CeO on the occurrence of the peaks is probed. For other rare-earth oxiae doped ceramics, such as Nd2O3. and Dy2O3. containing zirconia, the bulk and grain boundary resistances are evaluated by the impedance spectroscopy. The dependence of the associated activation energy in the rare-earth oxide doped zirconia is discussed with respect to the variation of the ionic radius of the rare earth constituent.

HRTEM Observation of α-Phase in Cu-Zn Alloy Annealed at Lower Temperature

2007 ◽  
Vol 26-28 ◽  
pp. 1279-1282 ◽  
Author(s):  
Koji Kato ◽  
Daisuke Hamatani ◽  
Kenji Matsuda ◽  
Tokimasa Kawabata ◽  
Yasuhiro Uetani ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Phase Decomposition ◽  
Β Phase ◽  
Α Phase ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Lower Temperature ◽  
Zn Alloy

It is known that the phase-decomposition process of 60/40 Cu-Zn alloy is so-called the bainitic transformation, and decomposition of α-phase from the β’-phase is as follow: β’ → α9R → αfcc. In this work,decomposition of α-phase from the β’ single phase of Cu-40.26at.%Zn alloy has been investigated by high-resolution transmission electron microscopy (HRTEM) to understand the phase transformation of this alloy. Especially, striations in the α-phase has been focused on the special feature for the change of the structure and hardening of this alloy during annealing. The result of a comparison between this alloy and the Si added alloy is also reported.

Microstructure and mechanical behavior of cast Ti-6Al-4V with addition of boron

2012 ◽  
Vol 2 (3) ◽  
Author(s):  
Robert Pederson ◽  
Raghuveer Gaddam ◽  
Marta-Lena Antti
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Room Temperature ◽  
Compressive Yield Strength ◽  
Strain Rates ◽  
Beta Transus ◽  
Microstructural Refinement ◽  
Compression Properties ◽  
Transus Temperature ◽  
Cast Microstructure

AbstractThe effect of boron (between 0.06 and 0.11 wt%) on the microstructure, hardness and compression properties of cast Ti-6Al-4V was investigated. Compression properties were examined in the temperature range from room temperature to 1000°C. It was found that the addition of boron refines the as-cast microstructure in terms of prior beta grain size and alpha colony size. This microstructural refinement led to an increase in compressive yield strength from room temperature up to 700°C. Three different strain rates (0.001, 0.1 and 1 s−1) were evaluated during compression testing from which it was found that the compressive yield strength decreased with decreasing strain rate from 600°C up to the beta transus temperature.

scholarly journals Thermal Behavior of Mg-Doped Calcium-Deficient Apatite and Stabilization of β Tricalcium Phosphate

2020 ◽  
Vol 10 (6) ◽  
pp. 6837-6845
Keyword(s):  
Tricalcium Phosphate ◽  
Inductively Coupled Plasma ◽  
Optical Emission ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Inductively Coupled ◽  
Β Phase ◽  
Beta Tricalcium Phosphate ◽  
Lower Temperature ◽  
Mg Doped

β-tricalcium phosphate (β-TCP) is a bioceramic with unique osteoinductive and osteoconductive properties. It can be obtained by calcining calcium-deficient apatites (CDHA) at 750°C and above. The reduction of calcining temperature or the stabilization of the β phase, by doping, is therefore of particular interest. This paper investigates the preparation of CDHA with a theoretical 0.05 Mg/(Ca + Mg) ratio and (Ca+Mg)/P = 1.55 via precipitation method, and the resultant powder is calcined at a different temperature ranging from 80 to 715°C. The as-synthesized undoped powder was used as the reference in this study. The effect of calcination temperature and composition were investigated by the aid of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma optical emission spectroscopy (ICP-OES) and scanning electron microscopy (SEM). The study indicated that the powder was pure Mg-doped beta-tricalcium phosphate. The incorporation of Mg within the calcium phosphate lattice promoted the formation and stabilization of the β -TCP phase at a lower temperature.

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