Preparation of pure α″-phase titanium alloys with low moduli via high pressure solution treatment

2017 ◽  
Vol 695 ◽  
pp. 45-51 ◽  
Author(s):  
Yang Zhang ◽  
Zhongyuan Liu ◽  
Zhisheng Zhao ◽  
Mingzhen Ma ◽  
Yu Shu ◽  
...  
Keyword(s):  
High Pressure ◽  
Titanium Alloys ◽  
Solution Treatment ◽  
Pressure Solution ◽  
Α Phase

The Role of Martensitic Transformation in Thermomechanical Development of Microstructure and Plasticity of Two-Phase Ti-6Al-4V Titanium Alloy

2016 ◽  
Vol 687 ◽  
pp. 3-10 ◽  
Author(s):  
Maciej Motyka ◽  
Jan Sieniawski ◽  
Waldemar Ziaja
Keyword(s):  
Plastic Deformation ◽  
Titanium Alloy ◽  
Martensitic Transformation ◽  
Titanium Alloys ◽  
Thermomechanical Processing ◽  
Solution Treatment ◽  
Phase Morphology ◽  
Two Phase ◽  
Α Phase ◽  
Hot Plasticity

Phase constituent morphology in microstructure of two-phase α+β titanium alloys is determined by conditions of thermomechanical processing consisting of sequential heat treatment and plastic deformation operations. Results of previous research indicate that particularly solution treatment preceding plastic deformation significantly changes α-phase morphology and determines hot plasticity of titanium alloys. In the paper thermomechanical processing composed of β solution treatment and following hot forging of Ti-6Al-4V titanium alloy was analysed. Development of martensite plates during heating up and hot deformation was evaluated. Microscopic examinations revealed that elongated and deformed α-phase grains were fragmented and transformed into globular ones. Significant influence of martensitic transformation on elongation coefficient of α-phase grains after plastic deformation was confirmed. Based on results of elevated temperature tensile tests it was established that α-phase morphology in examined two-phase α+β titanium alloy, developed in the thermomechanical processing, can enhance their hot plasticity – especially in the range of low strain rates.

Remarkable enhancement in precipitation hardening of Al7Si1.7Cu alloy by high pressure solution treatment

2018 ◽  
Vol 735 ◽  
pp. 378-381 ◽  
Author(s):  
Maowen Liu ◽  
Ruixiao Zheng ◽  
Wenlong Xiao ◽  
Qiuming Peng ◽  
Hiroshi Yamagata ◽  
...  
Keyword(s):  
High Pressure ◽  
Precipitation Hardening ◽  
Solution Treatment ◽  
Pressure Solution

Effect of High-Pressure Solution Temperature on Corrosion Resistance of AM60 Magnesium Alloy

2012 ◽  
Vol 580 ◽  
pp. 560-563
Author(s):  
Guang Hui Chen
Keyword(s):  
High Pressure ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Solution Treatment ◽  
Optical Microscope ◽  
Solution Temperature ◽  
Pressure Solution ◽  
Different Temperatures ◽  
Increasing Temperature

As-cast AM60 magnesium alloy was solid dissolved under a high-pressure of 4 Gpa at different temperatures. The microstructure of the products was observed by optical microscope and the corrosion resistance of the products was investigated. The results show that increasing temperature during solution treatment promotes the dissolution into α-Mg matrix of β-Mg17Al12 in the alloy and improves the corrosion resistance of AM60 alloy, especially for over 400 °C.

scholarly journals Strengthening of Ti-6Al-7Nb alloy by high-pressure torsion processing

2020 ◽  
Vol 321 ◽  
pp. 12002
Author(s):  
M. Ashida ◽  
P. Chen ◽  
Y. Tsutsumi ◽  
T. Hanawa ◽  
Z. Horita
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Tensile Strength ◽  
High Pressure Torsion ◽  
Solution Treatment ◽  
Good Balance ◽  
Ultrafine Grains ◽  
Α Phase ◽  
Microstructure And Mechanical Properties

A Ti-6Al-7Nb alloy with three different initial microstructures was processed by high-pressure torsion (HPT) and the resultant microstructure and mechanical properties of the alloy after HPT processing were investigated. The microstructure of the as-received alloy was an equiaxed (α+β) microstructure. The rods were subjected to solution treatment and aging (STA) treatment to obtain a bi-modal microstructure consisting of an equiaxed α phase and lamellar α+β phases, and those to solution treatment and quenching (STQ) treatment to obtain a bi-modal microstructure consisting of equiaxed α-phase and acicular α’-phase. Disks were cut from those rods and were processed by HPT under a pressure of 6 GPa. After HPT processing through 20 revolutions, the alloy with each of the three initial microstructures showed ultrafine grains with a size of ~70 nm. The alloy resulted in a higher tensile strength (1350 MPa) in both the bi-modal microstructures than that (1250 MPa) in the alloy with equiaxed α+β microstructure after HPT processing. It was shown that the Ti-6Al-7Nb alloy with the bi-modal microstructure was strengthened more than with the equiaxed α+β microstructure when the alloy was processed by HPT. Furthermore, the alloy with bi-modal microstructure consisting of equiaxed α-phase and acicular α’-phase showed a good balance between the tensile strength (1280 MPa) and the elongation to fracture (22%) after HPT processing through 1 revolution. In summary, therefore, large strength and elongation of the Ti-6Al-7Nb alloy were simultaneously achieved by HPT processing.

High-resolution EM investigation about effect of stress on formation of ω-phase crystals in β-tttanium alloys

1996 ◽  
Vol 54 ◽  
pp. 1006-1007
Author(s):  
E. Sukedai ◽  
M. Shimoda ◽  
A. Fujita ◽  
H. Nishizawa ◽  
H. Hashimoto
Keyword(s):  
High Resolution ◽  
Titanium Alloys ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Zone Refining ◽  
Ω Phase ◽  
Α Phase ◽  
Nucleation Sites ◽  
Resolution Electron ◽  
Bcc Structure

ω-phase particles formed in β-titanium alloys (bcc structure) act important roles to their mechanical properties such as ductility and hardness. About the ductility, fine ω-phase particles in β–titanium alloys improve the ductility, because ω-phase crystals becomes nucleation sites of α-phase and it is well known that (β+α) duplex alloys have higher ductility. In the present study, the formation sites and the formation mechanism of ω-phase crystals due to external stress and aging are investigated using the conventional and high resolution electron microscopy.A β-titanium alloy (Til5Mo5Zr) was supplied by Kobe Steel Co., and a single crystal was prepared by a zone refining method. Plates with {110} surface were cut from the crystal and were pressured hydrostatically, and stressed by rolling and tensile testing. Specimens for aging with tensile stress were also prepared from Ti20Mo polycrystals. TEM specimens from these specimens were prepared by a twin-jet electron-polishing machine. A JEM 4000EX electron microscope operated at 400k V was used for taking dark field and HREM images.

α Phase Growth and Branching in Titanium Alloys

2020 ◽  
Author(s):  
Deep Choudhuri ◽  
Rongpei Shi ◽  
Ankush Kashiwar ◽  
Sriswaroop Dasari ◽  
Rajarshi Banerjee ◽  
...  
Keyword(s):  
Titanium Alloys ◽  
Phase Growth ◽  
Α Phase

scholarly journals Design of Low-Cost and High-Strength Titanium Alloys Using Pseudo-Spinodal Mechanism through Diffusion Couple Technology and CALPHAD

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2910
Author(s):  
Chaoyi Ding ◽  
Chun Liu ◽  
Ligang Zhang ◽  
Di Wu ◽  
Libin Liu
Keyword(s):  
Diffusion Couple ◽  
Titanium Alloys ◽  
High Throughput ◽  
Volume Fraction ◽  
Raw Materials ◽  
Low Cost ◽  
High Strength ◽  
High Yield ◽  
Α Phase ◽  
Cr System

The high cost of development and raw materials have been obstacles to the widespread use of titanium alloys. In the present study, the high-throughput experimental method of diffusion couple combined with CALPHAD calculation was used to design and prepare the low-cost and high-strength Ti-Al-Cr system titanium alloy. The results showed that ultra-fine α phase was obtained in Ti-6Al-10.9Cr alloy designed through the pseudo-spinodal mechanism, and it has a high yield strength of 1437 ± 7 MPa. Furthermore, application of the 3D strength model of Ti-6Al-xCr alloy showed that the strength of the alloy depended on the volume fraction and thickness of the α phase. The large number of α/β interfaces produced by ultra-fine α phase greatly improved the strength of the alloy but limited its ductility. Thus, we have demonstrated that the pseudo-spinodal mechanism combined with high-throughput diffusion couple technology and CALPHAD was an efficient method to design low-cost and high-strength titanium alloys.

scholarly journals Oxygen Induced Phase Transformation in TC21 Alloy with a Lamellar Microstructure

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 163
Author(s):  
Shu Wang ◽  
Yilong Liang ◽  
Hao Sun ◽  
Xin Feng ◽  
Chaowen Huang
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Oxygen Uptake ◽  
Titanium Alloys ◽  
Electron Backscatter Diffraction ◽  
Lamellar Microstructure ◽  
Α Phase ◽  
Transmission Electron ◽  
The Matrix ◽  
Oxygen Ingress

The main objective of the present study was to understand the oxygen ingress in titanium alloys at high temperatures. Investigations reveal that the oxygen diffusion layer (ODL) caused by oxygen ingress significantly affects the mechanical properties of titanium alloys. In the present study, the high-temperature oxygen ingress behavior of TC21 alloy with a lamellar microstructure was investigated. Microstructural characterizations were analyzed through optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Obtained results demonstrate that oxygen-induced phase transformation not only enhances the precipitation of secondary α-phase (αs) and forms more primary α phase (αp), but also promotes the recrystallization of the ODL. It was found that as the temperature of oxygen uptake increases, the thickness of the ODL initially increases and then decreases. The maximum depth of the ODL was obtained for the oxygen uptake temperature of 960 °C. In addition, a gradient microstructure (αp + β + βtrans)/(αp + βtrans)/(αp + β) was observed in the experiment. Meanwhile, it was also found that the hardness and dislocation density in the ODL is higher than that that of the matrix.

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