γ→β phase transformation in Ti-42.9Al-4.6Nb–2Cr

2021 ◽  
Vol 133 ◽  
pp. 107169
Author(s):  
R.R. Xu ◽  
M.Q. Li
Keyword(s):  
Phase Transformation ◽  
Β Phase

Phase Transformation In Ti-6al-4v Alloys

1972 ◽  
Vol 30 ◽  
pp. 584-585
Author(s):  
Shiro Fujishiro
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Cryogenic Temperature ◽  
Β Phase ◽  
Heat Treated ◽  
Mixed Microstructure ◽  
Ductile Behavior

The Ti-6 wt.% Al-4 wt.% V commercial alloys have exhibited an improved formability at cryogenic temperature when the alloys were heat-treated prior to the tests. The author was interested in further investigating this unusual ductile behavior which may be associated with the strain-induced transformation or twinning of the a phase, enhanced at lower temperatures. The starting materials, supplied by RMI Co., Niles, Ohio were rolled mill products in the form of 40 mil sheets. The microstructure of the as-received materials contained mainly ellipsoidal α grains measuring between 1 and 5μ. The β phase formed an undefined grain boundary around the a grains. The specimens were homogenized at 1050°C for one hour, followed by aging at 500°C for two hours, and then quenched in water to produce the α/β mixed microstructure.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

Design Approaches and Achievements of Novel Wrought TiAl Alloys for Jet Engine Applications

MRS Advances ◽  
2019 ◽  
Vol 4 (25-26) ◽  
pp. 1465-1470
Author(s):  
Hideki Wakabayashi ◽  
Loris J. Signori ◽  
Ali Shaaban ◽  
Ryosuke Yamagata ◽  
Hirotoyo Nakashima ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Phase Transformation ◽  
Hot Workability ◽  
Tial Alloys ◽  
Jet Engine ◽  
Crack Propagation Resistance ◽  
Β Phase ◽  
Transformation Pathway ◽  
Component Systems ◽  
Multi Component System

AbstractDesign approaches and achievements for the development of wrought TiAl alloys to be used for LPT and HPC blades are constructed. In case of Ti-Al-M1-M2 quaternary systems, conventional equivalency concept does not work for the alloy design, and a new thermodynamic database for phase diagram calculations in multi-component systems of the alloys is built by introducing the interaction parameters among four phases of β−Ti, α2−Ti3Al, α−Ti and γ−TiAl phases in the systems, in order to reproduce the experimentally determined phase diagrams. Based on the phase diagram calculations, the composition range of a unique phase transformation pathway of β+α→α→β+γ in the multi-component system can be identified, and thus model alloys with excellent hot workability even at higher strain rate and mechanical properties can be successfully proposed. It can be concluded that an introduction of bcc β phase and the morphology control through the phase transformation pathway make it possible to improve the room temperature ductility, creep and fatigue crack propagation resistance.

Formation of a Novel X Phase in Mg–Gd–Zn–Zr Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 623-626 ◽  
Author(s):  
Y.J. Wu ◽  
Li Ming Peng ◽  
X.Q. Zeng ◽  
D.L. Lin ◽  
W.J. Ding
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Phase Transformation ◽  
Grain Boundaries ◽  
Solution Heat Treatment ◽  
Long Period ◽  
Β Phase ◽  
Lpso Structure ◽  
Zr Alloy ◽  
Zr Alloys

The coherent fine-lamellae consisting of the 2H-Mg and the 14H-type long period stacking ordered (LPSO) structure within α'-Mg matrix have been observed in an as-cast Mg–Gd–Zn–Zr alloy. During subsequent solid solution heat treatment at 773 K, in addition to the lamellae within matrix, a novel lamellar X phase [Mg–(8.37±1.0)Zn–(11.32±1.0)Gd] with the 14H-type LPSO structure was transformed from the dendritical β phase. The 14H-type LPSO structure existing in Mg–Gd–Zn–Zr alloys derives from two variant ways: formation of the 14H-type LPSO structure comes from two variant means: i.e., the formation within matrix and the phase transformation from the β phase to the X phase in grain boundaries.

2.45 GHz Microwave Sintering of Silicon Nitride

2008 ◽  
Vol 403 ◽  
pp. 27-30
Author(s):  
S. Chockalingam ◽  
J.P. Kelly ◽  
V.R.W. Amarakoon ◽  
James R. Varner
Keyword(s):  
Phase Transformation ◽  
Oxidation Behavior ◽  
Microwave Sintering ◽  
Sintered Sample ◽  
Microstructure Development ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Structurally Stable

Microwave sintered Si3N4-MgO system that contains 2, 4 and 10 wt% of ZrO2 as secondary particulates were investigated with respect to phase transformation and microstructure development. The experimental results of microwave sintered samples were compared with conventional methods. Complete α to β phase transformation was observed in the case of microwave sintered samples due to the volumetric nature of microwave heating. High temperature X-ray diffraction (HTXRD) analysis was performed to study in-situ the oxidation behavior of Si3N4 specimens. Si3N4 specimens with 10 wt % ZrO2 were exposed to air at temperature between 25°C and 900°C for up to 24 hours. Microwave sintered sample were structurally stable in air 25°C and 900°C for up to 24 hours of testing.

Phase Transformations of the Ti-40% Nb Alloy Under External Influence

2016 ◽  
Vol 683 ◽  
pp. 174-180 ◽  
Author(s):  
Yuri P. Sharkeev ◽  
Zhanna G. Kovalevskaya ◽  
Margarita A. Khimich ◽  
Vladimir A. Bataev ◽  
Qi Fang Zhu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Phase Transformation ◽  
Severe Plastic Deformation ◽  
Phase Transformations ◽  
Optical Metallography ◽  
External Influence ◽  
Β Phase ◽  
Α Phase ◽  
Pressing Operation ◽  
Loading Axis

The phase transformations of the alloy Ti-40 mas % Nb after tempering and severe plastic deformation are studied. The phase transformations of the alloy according to the type and conditions of external influences are analyzed using methods of XRD, SEM and optical metallography. It is determined that inverse phase transformation of the metastable α''-phase to equilibrium β-phase is carried out after severe plastic deformation. Complete phase transformation α'' → β is typical for the mode, which consists of three pressing operation with the change of the loading axis in cramped conditions, followed by a multi-pass rolling in grooved rolls.

Investigating Microstructural Changes and Phase Transformation During Slot Milling of Ti-6Al-4V in Dry, Flood Coolant and MQL Conditions

2019 ◽  
Author(s):  
Ashutosh Khatri ◽  
Muhammad P. Jahan ◽  
Xingbang Chen ◽  
Jianfeng Ma
Keyword(s):  
Phase Transformation ◽  
Cutting Speed ◽  
Thermal Softening ◽  
Phase Changes ◽  
Depth Of Cut ◽  
Dry Machining ◽  
Machined Surface ◽  
Microstructural Changes ◽  
Slot Milling ◽  
Β Phase

Abstract The objective of this study is to investigate the microstructural changes and phase transformation of chips and workpiece during slot milling on Ti-6Al-4V alloy in dry, flood coolant, and MQL conditions using uncoated carbide tools. The experiments were performed at varying feed rate and depth of cut with a fixed cutting speed of 50 m/min. The microstructures of the machined chips indicate that dry machining had the highest percentage of β-phase indicating higher phase transformation owing to higher tool temperature. The β-phase was found to be the least in MQL machining chips, which is very similar to the microstructural composition of un-machined surface. Although there were signs of phase transformation, there were very minimal changes in phases in the workpiece for all three machining conditions. In many cases, no change or slight decrease in β-phase was observed at the sub-surface, indicating thermal softening of the workpiece, especially in dry machining. The findings from this study confirm the fact that, high temperature close to beta transition temperature is generated during dry machining of titanium alloy, and most of heat is carried away by the chips resulting in phase transformation from alpha to beta phase in chips. However, no significant phase changes occurred into the microstructure of the workpiece in any condition, although minor thermal softening was found at the sub-surface of dry machined workpiece.

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