Microstructural stability, phase transformation and mechanical properties of a fully-lamellar microstructure of a Mo-modified high-Nb γ-TiAl alloy

2020 ◽  
Vol 784 ◽  
pp. 139313 ◽  
Author(s):  
H.Z. Niu ◽  
X.J. Chen ◽  
Y.F. Chen ◽  
S. Zhao ◽  
G.H. Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Tial Alloy ◽  
Lamellar Microstructure ◽  
Microstructural Stability ◽  
Fully Lamellar

Microstructures and Mechanical Properties of Ti-43Al-5V-4Nb-Y Alloy Consolidated by Spark Plasma Sintering

2016 ◽  
Vol 704 ◽  
pp. 183-189
Author(s):  
Yong Jun Su ◽  
Yi Feng Zheng ◽  
De Liang Zhang ◽  
Fan Tao Kong
Keyword(s):  
Mechanical Properties ◽  
Spark Plasma Sintering ◽  
Tial Alloy ◽  
Tensile Tests ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Short Period ◽  
Spark Plasma ◽  
Fully Lamellar

TiAl alloy with a composition of Ti-43Al-5V-4Nb-Y (at.%) was prepared by spark plasma sintering (SPS). The TiAl powders were sintered between 650°C and 1300°C for 5 min under different loads. With the increasing of the temperature, the diffusion of the elements can be observed. Full compaction is achieved in a short period of time and the overall processing duration does not exceed 30 min. A fully lamellar structure was seen in the TiAl alloy after heat treatment. The microstructures of the samples were determined by X-ray diffraction and scanning electron microscopy. Their mechanical properties were evaluated by tensile tests performed at room temperature

C11b/C40 Lamellar Structure in a Ta-added Molybdenum Disilicide

2000 ◽  
Vol 646 ◽  
Author(s):  
Fu-Gao Wei ◽  
Yoshisato Kimura ◽  
Yoshinao Mishima
Keyword(s):  
Mechanical Properties ◽  
Orientation Relationship ◽  
Binary Alloy ◽  
Lamellar Structure ◽  
Molybdenum Disilicide ◽  
Lamellar Microstructure ◽  
Polycrystalline Alloys ◽  
Lamellar Interface ◽  
Fully Lamellar ◽  
Microstructural Control

ABSTRACTC11b/C40 fully lamellar microstructures, similar to the well-known TiAl/Ti3Al lamellae, were obtained in Ta- and Nb-added MoSi2 polycrystalline alloys in a previous work. In the present study, the crystallography of the lamellar structure is investigated in a MoSi2-15mol%TaSi2 pseudo-binary alloy after homogenized at 1400°C for 168h, in order to provide some useful parameters for microstructural control to improve mechanical properties. The orientation relationship between C11b and C40 phases and its three distinct variants were identified. Coherency of the lamellar interface is analyzed in comparison with the TiAl/Ti3Al lamellae. Approach to modify the C11b/C40 lamellar microstructure to increase its coherency is discussed based on the results obtained.

The Effect of Heat Treatment on the Microstructure of Ti-45Al-5Nb-0.3Y Alloy

2009 ◽  
Vol 614 ◽  
pp. 55-59
Author(s):  
Fan Tao Kong ◽  
Yu Yong Chen
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Lamellar Microstructure ◽  
Air Cooling ◽  
Water Cooling ◽  
Different Temperatures ◽  
Combined Action ◽  
Average Size ◽  
Equiaxed Grains ◽  
Fully Lamellar

Effects of heat treatment on the microstructure of as-cast and as-forged Ti-45Al-5Nb-0.3Y alloy are discussed. The as-cast Ti-45Al-5Nb-0.3Y alloy exhibits a microstructure consisting of fine equiaxed grains which average size is almost 100μm. Phase transformation of as-cast Ti-45Al-5Nb-0.3Y alloy greatly depends upon cooling rate. During furnace cooling, the alloy transform to fully lamellar microstructure. During air cooling, massive transformation predominates. During oil cooling, extremely fine fully lamellar microstructure is formed. During water cooling, ordering α2 phases are primary. Thermo-mechanical treatments, through combined action of hot canned forging and heat treatment, were performed on a Ti-45Al-5Nb-0.3Y alloy to investigate their effect on the microstructure of the alloy. The as-forged Ti-45Al-5Nb-0.3Y alloy is comprised of a large number of dynamic recrystallization (DRX) γ grains, curved and broken lamellae, and a small amount of remnant lamellae. And three different microstructures, duplex (DP), nearly lamellar (NL) and fine fully lamellar (FFL), have been obtained through heat treatment at different temperatures (1320-1370°C), respectively.

Influence of Microstructure and Stress Ratio on Fatigue Crack Propagation in TiAl Alloy

2014 ◽  
Vol 881-883 ◽  
pp. 1330-1333 ◽  
Author(s):  
Yan Rui Zuo ◽  
Zhi Yuan Rui ◽  
Rui Cheng Feng ◽  
De Chun Luo ◽  
Chang Feng Yan
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Stress Ratio ◽  
Tial Alloy ◽  
Lamellar Microstructure ◽  
Propagation Resistance ◽  
Crack Propagation Resistance ◽  
Stress Ratios ◽  
Fully Lamellar

Based on the fatigue crack propagation experiments did by A.-L. Gloanec et al., the fatigue crack propagation rates of TiAl alloy of two processing routes, namely casting and PM, and stress ratios had been tested, in order to find out the effects of microstructure and stress ratio. An improved fatigue crack propagation formula for region Ⅱ (the expansion region) was derived according to Paris formula. The specific values of the constants in the formula were calculated. Fatigue crack propagation resistance of nearly fully lamellar microstructure is superior to that of equiaxed γ grain. The experimental results present that both microstructure and stress ratio has a significant influence on fatigue crack growth rate.

Role of Equiaxed Primary Alpha (α׳) and Mechanical Properties of Ti-6Al-4V Alloy

2012 ◽  
Vol 510-511 ◽  
pp. 420-428
Author(s):  
A. Ahmad ◽  
A. Ali ◽  
G.H. Awan ◽  
K.M. Ghauri ◽  
R. Aslam
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Volume Fraction ◽  
Lamellar Microstructure ◽  
Phase Region ◽  
Bimodal Microstructure ◽  
Two Phase ◽  
Primary Alpha ◽  
Fully Lamellar

The paper presents the role of equiaxed α׳ in the bimodal microstructure to attain an optimal combination of ductility and strength. The study revealed that the production of bimodal microstructure and volume fraction of equiaxed α׳ were reliant on the forging temperature and subsequent heat treatment. The Ti-6Al-4V alloy was forged in the two phase region and different heat treatment cycles were employed to get the desired bimodal microstructure and thus the combination of strength and ductility. The mechanical properties of fully lamellar microstructure were compared with bimodal microstructure containing equiaxed α׳. The experimental results showed that the amount of equiaxed α׳ in the bimodal microstructure was critical for achieving a well-balanced profile of mechanical properties.

scholarly journals Effect of Heat Treatment on Microstructures and Mechanical Properties of a Novel β-Solidifying TiAl Alloy

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1672 ◽  
Author(s):  
Ning Cui ◽  
Qianqian Wu ◽  
Kexiao Bi ◽  
Tiewei Xu ◽  
Fantao Kong
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fracture Toughness ◽  
Tial Alloy ◽  
Ductile Brittle Transition Temperature ◽  
Main Fracture ◽  
Microstructures And Mechanical Properties ◽  
Fully Lamellar ◽  
Fracture Features ◽  
Fracture Morphologies

The effect of heat treatment on the microstructures and mechanical properties of a novel β-solidifying Ti–43Al–2Cr–2Mn–0.2Y alloy was investigated. A fully lamellar (FL) microstructure with a colony size of about 100 μm was obtained by heat treatment at 1320 °C/10 min/furnace cooling (FC). A duplex (DP) microstructure with globular γ grains and γ/α2 lamellae was obtained by heat treatment at 1250 °C/4 h/FC. The residual hard–brittle β0 phase was also eliminated after heat treatment. The mechanical properties of the β-solidifying TiAl alloy depended closely on the heat treatment. The FL alloy had better fracture toughness, and the fracture toughness (KIC) value was 24.15 MPa·m1/2. The DP alloy exhibited better ductility, and the room temperature (RT) elongation of the alloy could reach 1%. The elongation of the alloy with different microstructures sharply increased when the temperature increased from 700 to 750 °C, indicating that the microstructure had no effect on the ductile–brittle transition temperature of the β-solidifying TiAl alloy. The fracture morphologies of different tensile specimens were observed. Interlamellar and translamellar fractures were the main fracture features of the FL alloy. Intergranular, translamellar, and interlamellar fractures were the main fracture features of the DP alloy.

scholarly journals The influence of microstructural characteristics on the mechanical properties of Ti6Al4V alloy produced by the powder metallurgy technique

2006 ◽  
Vol 71 (8-9) ◽  
pp. 985-992 ◽  
Author(s):  
Dusan Bozic ◽  
Ivana Cvijovic ◽  
Miroljub Vilotijevic ◽  
Milan Jovanovic
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Powder Metallurgy ◽  
Lamellar Microstructure ◽  
Ti6al4v Alloy ◽  
Globular Microstructure ◽  
Ductile Mode ◽  
Lower Porosity ◽  
Microstructural Morphology ◽  
Fully Lamellar

The influence of hot-pressing (HP-ing) parameters on the microstructure tensile properties and impact toughness of Ti6Al4V alloy produced by the powder metallurgy (PM) technique was evaluated. The experimental results show that variations in the microstructural morphology and residual porosity play an important role in affecting the mechanical properties of this alloy. The lamellar microstructure with a higher density, obtained by HP-ing above the ?-transition temperature (T?), was found to exibit a higher tensile strength and toughness than the globular microstructure produced below T?. Although both types of microstructure show a mixed fracture, the ductile mode was more pronounced in the case of the fully lamellar microstructure. By controlling the HP-ing pressure and duration time, the globular microstructure, with lower porosity, improved tensile strength and ductility in combination with a better resistance to crack initation and propagation can be obtained.

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