scholarly journals Hot Deformation Behavior and Microstructural Evolution of a Novel β-Solidifying Ti–43Al–3Mn–2Nb–0.1Y Alloy

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2172 ◽  
Author(s):  
Qianqian Wu ◽  
Ning Cui ◽  
Xiaohong Xiao ◽  
Xiaopeng Wang ◽  
Ertuan Zhao
Keyword(s):  
Tial Alloy ◽  
Processing Map ◽  
Large Angle ◽  
Deformation Condition ◽  
Hot Deformation Behavior ◽  
Tial Alloys ◽  
Ductile Brittle Transition Temperature ◽  
High Elongation ◽  
One Step ◽  
Average Size

In this paper, the hot deformability and mechanical properties of a novel Mn- and Nb- containing TiAl alloy were studied systematically with the use of isothermal compression experiments. The results show that the alloy has low deformation resistance and a low activation energy (392 KJ/mol), suggesting that the alloy has good hot deformability. A processing map was established, which shows that the present alloy has a smaller instability region and wider hot working window compared with other TiAl alloys. Microstructural observation shows that the initial lamellae completely transformed into fine equiaxial γ grains when the alloy was compressed at 1200 °C/0.01 s−1, which corresponds to the optimum deformation condition. Based on the above results, an intact TiAl billet was successfully fabricated by one-step large deformation using a four-column hydraulic machine. The microstructure of the billet is almost completely composed of recrystallized γ grains with large angle boundaries. Tensile testing shows the billet exhibits high tensile strength (780 MPa) and high elongation (1.44%) simultaneously, which benefits from fine γ grains with an average size of 4.9 μm. The ductile–brittle transition temperature is between 750–800 °C.

scholarly journals Effect of Multi-Directional Forging on the Microstructure and Mechanical Properties of β-Solidifying TiAl Alloy

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1381 ◽  
Author(s):  
Ning Cui ◽  
Qianqian Wu ◽  
Kexiao Bi ◽  
Jin Wang ◽  
Tiewei Xu ◽  
...  
Keyword(s):  
Tensile Properties ◽  
Room Temperature ◽  
Tial Alloy ◽  
Alloy Composition ◽  
Cast Alloy ◽  
Lamellar Microstructure ◽  
Hot Deformation Behavior ◽  
Tial Alloys ◽  
Β Phase ◽  
Ductile Brittle Transition Temperature

This study systematically investigated the influence of multi-directional forging (MDF) on the microstructural evolution, hot deformation behavior, and tensile properties of a β-solidifying TiAl alloy. The initial lamellar microstructure of an as-cast alloy was remarkably refined and homogenized by three-step MDF. High temperatures and multi-pass deformations were conducive to the decomposition of lamellae. A crack-free billet was obtained through three-step MDF, with a deformation temperature of 1250 °C and a forging speed of 0.1 mm/s, indicating that MDF can be applied to β-solidifying TiAl alloys by the proper control of the alloy composition and process parameters. Microstructural observation showed that the billet mainly consists of fine and equiaxed γ grains and a small amount of β phase. The tensile properties of the multi-directional forged alloy were also significantly improved, due to microstructure refinement. The ultimate tensile strength (UTS) and elongation (δ) at room temperature were 689.4 MPa, and 0.83%, respectively. The alloy exhibits excellent ductility at 700 °C. When the temperature was increased to 700 °C, the UTS decreased to 556 MPa and δ increased to 5.98%, indicating that the alloy exhibits excellent ductility at 700 °C. As the temperature further increased to 750 °C, δ dramatically increased to 46.65%, indicating that the ductile-brittle transition temperature of the alloy is between 700 °C and 750 °C.

scholarly journals The Microstructural Evolution, Tensile Properties, and Phase Hardness of a TiAl Alloy with a High Content of the β Phase

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2757 ◽  
Author(s):  
Ning Cui ◽  
Qianqian Wu ◽  
Zhiyuan Yan ◽  
Haitao Zhou ◽  
Xiaopeng Wang
Keyword(s):  
Tensile Properties ◽  
Room Temperature ◽  
Tial Alloy ◽  
Microstructural Analysis ◽  
Phase Content ◽  
Tial Alloys ◽  
Β Phase ◽  
Room Temperature Ductility ◽  
One Step ◽  
Equiaxed Grains

In this paper, the microstructure, deformability, tensile properties, and phase hardness of the Ti–43Al–2Cr–0.7Mo–0.1Y alloy with a high β phase content were investigated. Microstructural analysis showed that the β phase precipitated not only at the colony boundaries but also inside the lamellae due to its high content. A high-quality forging stock was prepared through one-step noncanned forging. The total deformation reached above 80%, suggesting that the alloy has good hot deformability compared to other TiAl alloys. The deformed microstructure was composed of fine and equiaxed grains due to dynamic recrystallization. The high β phase content was shown to contribute to the decomposition of the initial coarse lamellae. Tensile testing showed that the alloy has good room-temperature ductility, even if the β phase content reaches above 20%. This is inconsistent with a previous study that showed that a large amount of the hard β phase is detrimental to the room-temperature ductility of TiAl alloys. Nanoindentation testing showed that the hardness of the β phase in the current alloy is about 6.3 GPa, which is much lower than that in the Nb-containing TiAl alloys. Low hardness benefits the compatible deformation among various phases, which could be the main reason for the alloy’s good room-temperature ductility. Additionally, the influence of various β stabilizers on the hardness of the β phase was also studied. The β phase containing Nb had the highest hardness, whereas the β phase containing Cr had the lowest hardness.

Hot deformation behavior and processing map of low-alloy offshore steel

2021 ◽  
Author(s):  
Shi-ping Xi ◽  
Xin-liang Gao ◽  
Wei Liu ◽  
Yan-lu Lu ◽  
Gui-qin Fu ◽  
...  
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
Processing Map ◽  
Hot Deformation Behavior

scholarly journals Hot Deformation Behavior and Hot Rolling Properties of a Nano-Y2O3 Addition Near-α Titanium Alloy

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 837
Author(s):  
Zhuangzhuang Zheng ◽  
Yuyong Chen ◽  
Fantao Kong ◽  
Xiaopeng Wang ◽  
Yucheng Yu
Keyword(s):  
Activation Energy ◽  
Titanium Alloy ◽  
Hot Rolling ◽  
Deformation Behavior ◽  
Processing Map ◽  
Dynamic Recovery ◽  
Alloy Sheet ◽  
Hot Deformation Behavior ◽  
Hot Processing Map ◽  
Y2o3 Addition

The hot deformation behavior and hot rolling based on the hot processing map of a nano-Y2O3 addition near-α titanium alloy were investigated. The isothermal compression tests were conducted at various deformation temperatures (950⁠–1070 °C) and strain rates (0.001–1 s−1), up to a true strain of 1.2. The flow stress was strongly dependent on deformation temperature and strain rate, decreasing with increased temperature and decreased strain rate. The average activation energy was 657.8 kJ/mol and 405.9 kJ/mol in (α + β) and β region, respectively. The high activation energy and peak stress were contributed to the Y2O3 particles and refractory elements comparing with other alloys and composites. The deformation mechanisms in the (α + β) region were dynamic recovery and spheroidization of α phase, while the β phase field was mainly controlled by the dynamic recrystallization and dynamic recovery of β grains. Moreover, the constitutive equation based on Norton–Hoff equation and hot processing map were also obtained. Through the optimal processing window determined by the hot processing map at true strains of 0.2, 0.4 and 0.6, the alloy sheet with multi-pass hot rolling (1050 °C/0.03–1 s−1) was received directly from the as-cast alloy. The ultimate tensile strength and yield strength of the alloy sheet were 1168 MPa and 1091 MPa at room temperature, and 642 MPa and 535 MPa at 650 °C, respectively, which performs some advantages in current research.

Preparation and Characterization of Hybrid Graphene-ZnS Nanoparticles

2010 ◽  
Vol 663-665 ◽  
pp. 894-897
Author(s):  
Hua Huang ◽  
Hai Hu Yu ◽  
Ling De Zhou ◽  
Er Dan Gu ◽  
De Sheng Jiang
Keyword(s):  
Coupling Effect ◽  
Zinc Acetate Dihydrate ◽  
Graphene Sheets ◽  
Acetate Dihydrate ◽  
Zns Nanoparticles ◽  
Transmission Electron ◽  
Infrared Spectrometer ◽  
One Step ◽  
Average Size

Hybrid Graphene-ZnS nanopaticles (G-ZnS NPs) were prepared by using a solvothermal method. A dispersion of graphite oxide (GO) and zinc acetate dihydrate (Zn(CH3COO)2.2H2O) in dimethl sulfoxide (DMSO) reacted at 180 °C for 12 h in a Telfon-lined stainless steel autoclave. In the reaction, DMSO serves as a sulphide source as well as a reducing agent, resulting formation of the hybrid G-ZnS NPs in one-step. Hybrid G-ZnS NPs were characterized by using a powder X-ray diffractometer, a Fourier-transform infrared spectrometer, a transmission electron microscope, a UV-vis spectrophotometer and a fluorescence spectrophotometer, respectively. In the FTIR spectra, the GO related stretching bands of C-O and carboxyl groups are not observed in the spectra of G-ZnS, suggesting that the GO sheets were reduced to graphene sheets. In the TEM images, it is observed that the ZnS nanoparticles with an average size of 23 nm are attached onto the graphene sheets. The UV-vis absorption spectrum of the G-ZnS NPs dispersed in ethanol has an absorption peak of G at 261 nm and a weak shoulder of ZnS NPs around 320 nm. The broadening and weakening of the peak of ZnS NPs at 320 nm arises from the interparticle coupling effect. Under excitation at 225 nm, a peak around 386 nm and other weaker bands appear in the fluorescence spectrum of the G-ZnS. The band at 386 nm is attributed to zinc vacancies.

Hot deformation behavior and workability characteristic of a fine-grained Mg‒8Sn‒2Zn‒2Al alloy with processing map

2019 ◽  
Vol 35 (6) ◽  
pp. 1198-1209 ◽  
Author(s):  
Weili Cheng ◽  
Yang Bai ◽  
Shichao Ma ◽  
Lifei Wang ◽  
Hongxia Wang ◽  
...  
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
Processing Map ◽  
Hot Deformation Behavior ◽  
Fine Grained
Sign in / Sign up

Export Citation Format

Share Document