scholarly journals Deformation and Phase Transformation of Disorder α Phase at (α+γ) two Phase Region in high Nb Containing TiAl alloy

2021 ◽  
Author(s):  
Haitao Zhou ◽  
Fantao Kong ◽  
Yanbo Wang ◽  
Xiangwu Hou ◽  
Ning Cui ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Microstructural Evolution ◽  
Microstructure Evolution ◽  
Tial Alloy ◽  
Temperature Drop ◽  
Alpha Phase ◽  
Phase Region ◽  
Two Phase ◽  
Α Phase ◽  
Assisted Decomposition

In this paper, the deformation and phase transformation of disorder α phase at (α + γ) two phase region in as-forged Ti-44Al-8Nb-(W, B, Y) alloy are investigated by hot compression and hot packed rolling. Detailed microstructural evolution demonstrates that the as-deformed microstructure is significantly affected by deformation conditions. The mircrostructure differences are mainly due to temperature drop and strain rate. The evolution of α lamelae into α grains is detailed descripted. Moreover, the disorder α lamellae can also be decomposed into some new α grains by the assisted decomposition mechanism of γ grains. Microstructure evolution model of current TiAl alloy at 1250 °C during hot rolling is built.

scholarly journals Deformation and Phase Transformation of Disordered α Phase in the (α + γ) Two-Phase Region of a High-Nb TiAl Alloy

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4817
Author(s):  
Haitao Zhou ◽  
Fantao Kong ◽  
Yanbo Wang ◽  
Xiangwu Hou ◽  
Ning Cui ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Dynamic Recrystallization ◽  
Hot Rolling ◽  
Tial Alloy ◽  
Phase Region ◽  
Two Phase ◽  
Continuous Dynamic Recrystallization ◽  
Α Phase ◽  
Continuous Dynamic ◽  
Lower Temperature

In this paper, the deformation and phase transformation of disordered α phase in the (α + γ) two-phase region in as-forged Ti-44Al-8Nb-(W, B, Y) alloy were investigated by hot-compression and hot-packed rolling. The detailed microstructural evolution demonstrated that the deformed microstructure was significantly affected by the deformation conditions, and the microstructure differences were mainly due to the use of a lower temperature and strain rate. Finer α grains were formed by the continuous dynamic recrystallization of α lamellae and α grains distributed around lamellar colonies. Moreover, the grooved γ grains formed by the phase transformation from α lamellae during hot rolling cooperated with and decomposed α lamellae. A microstructure evolution model was built for the TiAl alloy at 1250 °C during hot rolling.

scholarly journals An Ultra Small Angle Scattering Study of Hydrogen in Metals

1982 ◽  
Vol 37 (5) ◽  
pp. 512-516 ◽  
Author(s):  
D. Bader ◽  
H. Rauch ◽  
A. Zeilinger
Keyword(s):  
Lattice Gas ◽  
Angular Position ◽  
Phase Region ◽  
Two Phase ◽  
Interstitial Solution ◽  
Α Phase ◽  
Angle Scattering ◽  
Scattering Study ◽  
Adjustment System ◽  
Better Than

A diffractometer using perfect crystals in symmetric Bragg arrangement, hence being useful for both neutron and X-ray radiation, has been built. The angular resolution of that instrument is better than 1 microradian, which corresponds to a scattering vector resolution of about 10-6 Å-1. This spectrometer was equipped with a laser light adjustment system which is sensitive to the relative angular position of the two perfect crystals. The spectrometer was used for the mea­surement of neutron scattering at very low angles of hydrated niobium and vanadium samples. The experimental results show an anomalously low attenuation of the neutrons when the metal-H sample is within the solubility a region. This property is explained by a lattice gas model of atomic H in the α-phase of the system. In the two phase region (α - β) a stronger attenuation of the neutron beam occurs due to the sample now being in an ordered interstitial solution phase.

scholarly journals Effect of Reverse-phase Transformation Annealing Process on Microstructure and Mechanical Properties of Medium Manganese Steel

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1633 ◽  
Author(s):  
Yan Zhao ◽  
Lifeng Fan ◽  
Bin Lu
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Volume Fraction ◽  
Lath Martensite ◽  
Phase Region ◽  
Manganese Steel ◽  
Reverse Phase ◽  
Two Phase ◽  
Fine Grain ◽  
Martensite Microstructure

In order to develop a third-generation automobile steel with powerful strength and elongation, we propose a method through high temperature quenching and two-phase region reverse-phase transformation annealing to develop such steel with 0.13% C and 5.4% Mn. To investigate the microstructure evolution and mechanical properties of manganese steel, SEM, XRD and TEM are employed in our experiments. Experimental results indicate that the microstructure after quenching is mainly lath martensite microstructure with average of lath width at 0.5 μm. The components of the steel after along with reverse-phase transformation annealing are ultra-fine grain ferrite, lath martensite and different forms of austenite microstructure. When the temperature at 625 °C, the components of the steel mainly includes lath martensite microstructure and ultra-fine grain ferrite and the fraction of austenite volume is only 5.09%. When the annealing temperature of reverse-phase transformation increase into 650 °C and 675 °C, the austenite appears in the boundary of the ferritic grain boundary and the boundary of lath martensite as the forms of bulk and lath. The phenomenon appears in the bulk of austenite, and the size of is 0.22 μm, 0.3 μm. The fraction of austenite volume is 22.34% at 675 °C and decreases into 9.32% at 700 °C. The components of austenite mainly includes ultra-fine grained ferrite and lath martensite. Furthermore, the density of decreases significantly, and the width of martensite increases into 0.32 μm. In such experimental settings, quenching at 930 °C with 20 min and at 675 °C with 30 min reverse-phase transformation annealing, the austenite volume fraction raises up to 22.34%.

scholarly journals Aging Behavior and Precipitation Analysis of Cu-Ni-Co-Si Alloy

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 435
Author(s):  
Xiangpeng Xiao ◽  
Jian Huang ◽  
Jinshui Chen ◽  
Hai Xu ◽  
Zhao Li ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Aging Process ◽  
Kinetic Curve ◽  
Kinetic Equations ◽  
Phase Region ◽  
Transformation Kinetic ◽  
Precipitation Kinetic ◽  
Two Phase ◽  
Transmission Electron ◽  
Co Addition

Cu-Ni-Si alloy with a different Co content was prepared by inductive melting and hot rolling. The alloy was solution treated at 950 °C for 1.5 h and aged at 450 °C, 500 °C, and 550 °C for different times. The phase diagram calculation and transmission electron microscopy was used to investigate the effect of Co addition on the aging precipitation behavior of the Cu-Ni-Si alloy. The phase transformation kinetics equation was calculated as well. The results show that, with the increase of aging temperature, the two-phase region of Fcc + Ni2Si in the Cu-Ni-Si ternary diagram would get wider. Some NixSiy phases would also form in the Cu-rich isothermal section. The addition of Co would replace part of Ni to form the (Ni, Co)2Si phase, which inhibits the spinodal decomposition process of the Cu-Ni-Si alloy during the aging process. The precipitated phase of the Cu-Ni-Si alloy with a high content of the Co element is more likely to grow with the extension of aging time. The phase transformation kinetic equations of the Cu-Ni-Si alloy at 450 °C and 500 °C showed good agreement with the experimental results. Furthermore, it can be seen from the precipitation kinetic curve the addition of the Co element accelerates precipitation in the aging process.

Microstructure evolution during deformation of a near-α titanium alloy with different initial structures in the two-phase region

2009 ◽  
Vol 61 (4) ◽  
pp. 419-422 ◽  
Author(s):  
Behrang Poorganji ◽  
Makoto Yamaguchi ◽  
Yoshio Itsumi ◽  
Katsushi Matsumoto ◽  
Tomofumi Tanaka ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Microstructure Evolution ◽  
Phase Region ◽  
Two Phase

Mechanical Behaviour and Microstructure Evolution of Severely Deformed Two-Phase Titanium Alloys

2008 ◽  
Vol 584-586 ◽  
pp. 771-776 ◽  
Author(s):  
Sergey V. Zherebtsov ◽  
Sergey Mironov ◽  
Maria A. Murzinova ◽  
S. Salishchev ◽  
S. Lee Semiatin
Keyword(s):  
Titanium Alloys ◽  
Microstructure Evolution ◽  
High Strain ◽  
Beta Phase ◽  
Alpha Phase ◽  
Steady State Flow ◽  
Two Phase ◽  
Globular Microstructure ◽  
Flow Response ◽  
Alpha Beta

Microstructure evolution and mechanical behavior of alpha/beta Ti-6Al-4V (VT6) and near-beta Ti-5Al-5Mo-5V-1Cr-1Fe (VT22) titanium alloys during uniaxial compression at 600°C to a high strain of 70% was studied. The plastic-flow response for both alloys is characterized by successive stages of strain hardening, flow softening, and steady-state flow. During compression the lamellae spheroidized to produce a partially globular microstructure. Globularization in VT6 is associated with the loss of the initial Burgers-type coherency between the alpha and beta phases and the subsequent individual deformation of each phase. The misorientations of boundaries increase to the high-angle range by means of the accumulation of lattice dislocations. In VT22 alloy the alpha phase evolves similar to that in VT6 alloy, while in the beta phase mainly low-angle boundaries are observed even after 70 pct. reduction.

Effect of Two-Phase Region Quenching Temperature on Microstructure Evolution and Microhardness of HSLA100 Steel

2012 ◽  
Vol 602-604 ◽  
pp. 380-384
Author(s):  
X. Yan ◽  
G.F. Zhou ◽  
C.M. Zhu ◽  
J.S. Guan
Keyword(s):  
Microstructure Evolution ◽  
Volume Fraction ◽  
High Strength ◽  
Phase Region ◽  
Two Phase ◽  
Quenching Temperature ◽  
Island Structure ◽  
Transmission Electron ◽  
Evolution Characteristics ◽  
Lath Bainite

The microstructure evolution characteristics and those effects on microhardness of HSLA (high strength low alloy) 100 steel secondary quenched in the two-phase region were investigated. The results show that the mixed microstructure of ferrite and the M-A（mastenite-austenite）islands can be obtained in the intercritical quenching region. A small amount of island structure distributing along the lath ferrite quenched at 700°C is observed by transmission electron microscope (TEM). With the quenching temperature increasing, the island structure increases in quantity and coarsens in shape, at the same time, the ferrite gradually transform from single lath morphology to polygonal shape with the dislocation density lowing. When quenched at 820°C, the microstructure reverts to lath bainite. There is a good correlation between Vickers hardness value and the volume fraction of martensite or bainite HSLA100 steel quenched in the two-phase region. The microhardness value of the steel continually increase from 240HV to 320HV quenched at the range of 700°C to 820°C, and then keep a very small fluctuation around 320HV when the temperature exceeds to 820°C.

The Prediction of the Flow Stress of an Extra-Low Carbon Steel in the Two-Phase Region Using Continuous Cooling Curves

1996 ◽  
Vol 118 (4) ◽  
pp. 463-470 ◽  
Author(s):  
Yhu-Jen Hwu ◽  
J. G. Lenard ◽  
J. J. M. Too
Keyword(s):  
Phase Transformation ◽  
Flow Stress ◽  
Carbon Steel ◽  
Volume Fraction ◽  
Low Carbon Steel ◽  
Phase Region ◽  
Cooling Curves ◽  
Low Carbon ◽  
Two Phase ◽  
Continuous Cooling

Continuous cooling curves of an extra-low carbon steel under three cooling rates are measured. The flow stress of the steel is established in compression tests during which the temperature is continuously decreasing. The phase transformation temperatures are determined from the cooling rate curve. The latent heat during phase transformation is calculated. A new variable, related to the volume fraction of transformation, is defined. Experimental results show that the relationship between the softening ratio of the flow stress due to phase transformation and this new variable may be described by a quadratic relationship. Based on this relationship and the continuous cooling curves, the flow stresses in the two-phase region are successfully predicted.

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