scholarly journals Strengthening of a Near β-Ti Alloy through β Grain Refinement and Stress-Induced α Precipitation

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4255 ◽  
Author(s):  
Wei Chen ◽  
Chao Li ◽  
Kangtun Feng ◽  
Yongcheng Lin ◽  
Xiaoyong Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Strength ◽  
Ti Alloy ◽  
Β Phase ◽  
Ti Alloys ◽  
Α Phase ◽  
Transmission Electron ◽  
Strength And Ductility ◽  
Α Particles

Near β-Ti alloys with high strength and good ductility are desirable for application in aviation and aerospace industries. Nevertheless, strength and ductility are usually mutually exclusive in structural materials. Here we report a new thermo-mechanical process, that is, the alloy was cross-rolled in β field then aged at 600 °C for 1 h. By such a process, a high strength (ultimate tensile strength: 1480 MPa) and acceptable ductility (elongation: 10%) can be simultaneously achieved in the near β-Ti alloy, based on the microscale β matrix and nanoscale α phase. The microstructure evolution, mechanical properties and strengthening mechanisms have been clarified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the grain size of the β phase progressively decreased with the increasing of rolling reduction. Moreover, dense dislocation structures and martensite phases distributed in the cross-rolled β matrix can effectively promote the precipitation of nanoscale α particles. TEM analyses confirmed that a heat-treatment twin was generated in the newly formed α lath during aging. These findings provide insights towards developing Ti alloys with optimized mechanical properties.

Study on the Microstructure and Properties of Low Cost TiFeAl Alloy

2013 ◽  
Vol 477-478 ◽  
pp. 1288-1292
Author(s):  
Bo Long Li ◽  
Tong Liu ◽  
Jie Yuan ◽  
Zuo Ren Nie
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Low Cost ◽  
High Strength ◽  
Al Alloys ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Β Phase ◽  
Transmission Electron ◽  
Solution Strengthening

The high strength and low cost Ti-Fe based alloy was produced by double vacuum induction melting method followed by hot deformation. The microstructure has been investigated by Optical Microscopy, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The microstructure of as-forged alloy is composed of α and β phase without the precipitation of TiFe intermetallic compound. The Ti-Fe-Al alloys show good comprehensive mechanical properties, demonstrating ultimate tensile strength of 1100MPa and elongation above10%. The results indicate the Fe is a good candidate for solution strengthening and simultaneously increasing ductility in titanium alloys. Effect of the Fe and Al elements on the microstructure and mechanical properties have been discussed.

Effect of Alloying and Thermal Processing on Mechanical Properties of TiAl Alloys

2016 ◽  
Vol 258 ◽  
pp. 501-505
Author(s):  
Alice Chlupová ◽  
Milan Heczko ◽  
Karel Obrtlík ◽  
Přemysl Beran ◽  
Tomáš Kruml
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Processing ◽  
Lamellar Microstructure ◽  
High Strength ◽  
Fatigue Behaviour ◽  
Tial Alloys ◽  
Working Temperature ◽  
Β Phase ◽  
Strength And Ductility

Two γ-based TiAl alloys with 7 at.% of Nb, alloyed with 2 at.% Mo and 0.5 at.% C, were studied. A heat treatment leading to very fine lamellar microstructure was applied on both alloys. Microstructure after the heat treatment was described and mechanical properties including fatigue behaviour were measured. The as-received material alloyed with C possesses high strength and very limited ductility, especially at RT. After application of selected heat treatment it becomes even more brittle; therefore, this process could be considered as not appropriate for this alloy. On the contrary, in the case of Mo alloyed material, both strength and ductility are improved by the heat treatment at RT and usual working temperature (~750 °C). Presence of the β phase is responsible for this effect. The selected heat treatment thus can be an alternative for this alloy to other thermomechanical treatments as high temperature forging.

scholarly journals Study on Grain Refinement Mechanisms and Mechanical Properties of bi-Modal Ti-55511 Titanium Alloy during Hot Rolling

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3351 ◽  
Author(s):  
Wei Chen ◽  
Xiaoyong Zhang ◽  
YongCheng Lin ◽  
Kechao Zhou
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hot Rolling ◽  
Shear Bands ◽  
High Ductility ◽  
Α Phase ◽  
Transmission Electron ◽  
Scanning Electron

Multi-pass hot rolling was performed on bi-modal Ti-55511 alloy with 50% rolling reduction at 700 °C. Mechanical properties were evaluated by tensile test, and microstructure evolution was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the Ti-55511 alloy with bi-modal microstructure exhibits good strength and high ductility (1102 MPa, 21.7%). Comparatively, after 50% hot rolling, an enhanced strength and decreased ductility were obtained. The refinement of α phases leads to the increased tensile strength, while the fragmentation of the equiaxed α phase results in a decreased ductility. The fragmentation process of equiaxed α phases followed the sequence of: elongation of α phases → formation of grooves and localized shear bands → the final fragmentation accomplished via deepening grooves.

scholarly journals A novel high-strength β-Ti alloy with hierarchical distribution of α-phase: The superior combination of strength and ductility

2019 ◽  
Vol 168 ◽  
pp. 107640 ◽  
Author(s):  
Wenguang Zhu ◽  
Jia Lei ◽  
Changsheng Tan ◽  
Qiaoyan Sun ◽  
Wei Chen ◽  
...  
Keyword(s):  
High Strength ◽  
Ti Alloy ◽  
Α Phase ◽  
Strength And Ductility

Effect of Processing Route on Mechanical Behavior of C-Mn Multiphase High Strength Cold Rolled Steel

2007 ◽  
Vol 539-543 ◽  
pp. 4375-4380
Author(s):  
Dagoberto Brandão Santos ◽  
Élida G. Neves ◽  
Elena V. Pereloma
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Quantitative Relationship ◽  
High Strength ◽  
Microstructural Characterization ◽  
Processing Route ◽  
Accelerated Cooling ◽  
Microstructural Parameters ◽  
Transmission Electron

The multiphase steels have complex microstructures containing polygonal ferrite, martensite, bainite, carbide and a small amount of retained austenite. This microstructure provides these steels with a high mechanical strength and good ductility. Different thermal cycles were simulated in the laboratory in order to create the microstructures with improved mechanical properties. The samples were heated to various annealing temperatures (740, 760 or 780°C), held for 300 s, and then quickly cooled to 600 or 500°C, where they were soaked for another 300 s and then submitted to the accelerated cooling process, with the rates in the range of 12-30°C/s. The microstructure was examined at the end of each processing route. The mechanical behavior evaluation was made by microhardness testing. The microstructural characterization involved optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) with electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM). The use of multiple regression analysis allowed the establishment of quantitative relationship between the microstructural parameters, cooling rates and mechanical properties of the steel.

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.

scholarly journals Modulation of Multiple Precipitates for High Strength and Ductility in Al-Cu-Mn Alloy

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7383
Author(s):  
Linxiang Liu ◽  
Zhijun Wang ◽  
Qingfeng Wu ◽  
Zhongsheng Yang ◽  
Kexuan Zhou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Tensile Strength ◽  
High Strength ◽  
Mechanical Behaviors ◽  
High Tensile Strength ◽  
Transmission Electron ◽  
Evolution Pattern ◽  
Elongation To Failure ◽  
High Elongation ◽  
Strength And Ductility

The category and morphology of precipitates are essential factors in determining the mechanical behaviors of aluminum alloys. It is a great challenge to synthetically modulate multiple precipitates to simultaneously improve strength and ductility. In the present work, by optimizing the precipitations of the GP zone, θ’-approximant and θ’ phase for an Al-Cu-Mn alloy, a high tensile strength of 585 MPa with large elongation of 12.35% was achieved through pre-deformation and aging. The microstructure evolution pattern was revealed by detailed characterizations of scanning electron microscopy and transmission electron microscopy. It was found that such high tensile strength of the samples was due to a combination of strengthening by the high density of dispersive fine precipitates and dislocations, and the high elongation to failure was primarily attributed to the multimodal precipitates and elimination of precipitation-free zones along the grain boundaries. The strategy proposed here is a promising way of preparing ultra-strong Al-Cu-Mn alloys.

scholarly journals Correlation between the Microstructure and Mechanical Properties of W-Bearing Ti-6Al-4V Alloys

2021 ◽  
Vol 59 (6) ◽  
pp. 357-364
Author(s):  
Godwin Kwame Ahiale ◽  
In-Seok Kye ◽  
Young Sam Kwon ◽  
Yong-Jun Oh
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Solid Solution Hardening ◽  
Powder Injection ◽  
Injection Molding Process ◽  
Molding Process ◽  
Β Phase ◽  
Α Phase ◽  
The Matrix ◽  
Indentation Tests

W-containing Ti-6Al-4V alloys (W=0, 1, and 5 wt%) were fabricated by the powder injection molding process, and the corresponding effects of tungsten content on the mechanical properties and microstructure of the alloys were investigated. The alloy powders were sintered at 1200 °C and then hot-isostatically-pressed at 900 °C. The fabricated alloys were subjected to microstructural and chemical analyses, and tensile and nano-indentation tests. The yield strength and tensile strength proportionally increased as the W content was increased from 0 wt% to 5 wt%. Ductility was not affected by the addition of up to 5 wt% W due to its complete dissolution in the matrix. Higher W addition induced finer α/β lamellar microstructures and increased the β to α phase ratio. Moreover, the added W dissolved preferentially in the β phase by solid solution hardening, increasing the hardness of the β phase, which originally was significantly softer than the α phase. For the alloys containing up to 5 wt% W, the strengthening without ductility loss was attributed to the finer α/β lamellae and the volume increase in the β phase hardened by W. These results suggest that adding W to Ti-6Al-4V alloy is a promising method for developing Ti alloys with both high strength and toughness.

scholarly journals Omega Phase Formation in Ti–3wt.%Nb Alloy Induced by High-Pressure Torsion

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2262
Author(s):  
Anna Korneva ◽  
Boris Straumal ◽  
Askar Kilmametov ◽  
Alena Gornakova ◽  
Anna Wierzbicka-Miernik ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Phase Transformations ◽  
Grain Refinement ◽  
High Pressure Torsion ◽  
Β Phase ◽  
Ω Phase ◽  
Α Phase ◽  
Transmission Electron ◽  
Different Temperatures

It is well known that severe plastic deformation not only leads to strong grain refinement and material strengthening but also can drive phase transformations. A study of the fundamentals of α → ω phase transformations induced by high-pressure torsion (HPT) in Ti–Nb-based alloys is presented in the current work. Before HPT, a Ti–3wt.%Nb alloy was annealed at two different temperatures in order to obtain the α-phase state with different amounts of niobium. X-ray diffraction analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied for the characterisation of phase transitions and evolution of the microstructure. A small amount of the β-phase was found in the initial states, which completely transformed into the ω-phase during the HPT process. During HPT, strong grain refinement in the α-phase took place, as did partial transformation of the α- into the ω-phase. Therefore, two kinds of ω-phase, each with different chemical composition, were obtained after HPT. The first one was formed from the β-phase, enriched in Nb, and the second one from the α-phase. It was also found that the transformation of the α-phase into the ω-phase depended on the Nb concentration in the α-Ti phase. The less Nb there was in the α-phase, the more of the α-phase was transformed into the ω-phase.

Reinforcement of Electrospun Nonwovens

2011 ◽  
Vol 175-176 ◽  
pp. 121-126 ◽  
Author(s):  
Xin Sheng Zhu ◽  
Qiang Gao ◽  
Xiao Li Shi ◽  
Qian Qian Pan ◽  
Xiao Shan Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Interfacial Adhesion ◽  
High Strength ◽  
Mechanical Measurement ◽  
Polymer Blending ◽  
Transmission Electron ◽  
Carbon Nano Tubes ◽  
Nonwoven Mats ◽  
Scanning Electron

In this paper, the solvent mixing, polymer blending, multi-walled carbon nano-tubes(MWCNTs) reinforcing, steaming and heat treatments, and multi-layering with spunbond nonwoven were used to enhance the mechanical properties of the electrospun nonwovens of polystyrene(PS), polyvinyl chloride(PVC) and poly(phthalazinone ether sulfone ketone)(PPESK). The scanning electron microscopy, transmission electron microscopy and mechanical measurement were applied to characterize their microstructure and properties. The results showed that, the optimal mixture solvent can increase the tensile strength of PVC nonwovens by over 5 times; the polymer blending substantially improves the mechanical properties of PPESK nonwovens since the mechanical properties of virgin PPESK was so fragile that no data were obtained; the addition of MWCNTs to PS, PVC and PPESK improves their mechanical strength; the steaming and heating measures can be good viable route to lead to high strength for all of them; the multi-layering technique by using common spunbond nonwovens can be used to strengthen the nonwoven mats if the interfacial adhesion between the two mats can be solved well.

Sign in / Sign up

Export Citation Format

Share Document