Dispersoid Modification of Ti3Al-Nb Alloys

1985 ◽  
Vol 58 ◽  
Author(s):  
R. G. Rowe ◽  
J. A. Sutliff ◽  
E. F. Koch
Keyword(s):  
Fracture Toughness ◽  
Rare Earth ◽  
Titanium Aluminide ◽  
Melt Spinning ◽  
Room Temperature ◽  
Beta Transus ◽  
Processing Conditions ◽  
Room Temperature Ductility ◽  
Rapidly Solidified ◽  
Titanium Aluminide Alloys

ABSTRACTTitanium aluminide alloys with matrix compositions of essentially Ti3Al plus 0, 5, 7.5, and 10 a/o Nb and with and without rare earth elements for dispersoid formation were prepared. The alloys were rapidly solidified by melt spinning. Ribbon was consolidated by HIP and extrusion at temperatures below the beta transus temperatures of the alloys. The effects of processing conditions and dispersoid additions on room temperature ductility and fracture toughness were studied.

Rare Earth Oxide Dispersoid Stability and Microstructural Effects in Rapidly Solidified Ti3Al and Ti3A1-Nb

1985 ◽  
Vol 58 ◽  
Author(s):  
J. A. Sutliff ◽  
R. G. Rowe
Keyword(s):  
Rare Earth ◽  
Titanium Aluminide ◽  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
Rare Earth Oxide ◽  
Microstructural Effects ◽  
Analytical Electron ◽  
The Matrix ◽  
Rapidly Solidified ◽  
Titanium Aluminide Alloys

ABSTRACTThe microstructures of titanium aluminide alloys containing a rare earth oxide dispersion have been characterized using analytical electron microscopy. The alloys, based on Ti3A1 (alpha-2), contained 0 to 10.7 atom% Nb and 0.5 atom% Er. Alloys were rapidly solidified by melt spinning and were subsequently consolidated by HIP and extrusion. The microstructure of each alloy was examined in the as-cast, as-HIP'ed, and as-extruded conditions. A fine dispersoid spaced less than 100 nm apart was observed in ribbon aged at 750°C. The effects of processing conditions on the dispersoid distribution as a function of matrix chemistry were studied. Hot deformation was also examined to investigate the nature of the interaction between the dispersoids and the matrix during deformation.

scholarly journals Development of TiAl–Si Alloys—A Review

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1030
Author(s):  
Anna Knaislová ◽  
Pavel Novák ◽  
Marcello Cabibbo ◽  
Lucyna Jaworska ◽  
Dalibor Vojtěch
Keyword(s):  
Titanium Aluminide ◽  
Room Temperature ◽  
High Hardness ◽  
Tool Steels ◽  
Good Resistance ◽  
Intermetallic Materials ◽  
Room Temperature Ductility ◽  
Resistance To Oxidation ◽  
Process Structure ◽  
Titanium Aluminide Alloys

This paper describes the effect of silicon on the manufacturing process, structure, phase composition, and selected properties of titanium aluminide alloys. The experimental generation of TiAl–Si alloys is composed of titanium aluminide (TiAl, Ti3Al or TiAl3) matrix reinforced by hard and heat-resistant titanium silicides (especially Ti5Si3). The alloys are characterized by wear resistance comparable with tool steels, high hardness, and very good resistance to oxidation at high temperatures (up to 1000 °C), but also low room-temperature ductility, as is typical also for other intermetallic materials. These alloys had been successfully prepared by the means of powder metallurgical routes and melting metallurgy methods.

Effect of Rolling Parameters on the Properties of Al-Fe-V Sheet Rolled on an Experimental Mill

1985 ◽  
Vol 58 ◽  
Author(s):  
A. Brown ◽  
D. Raybould
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Aluminum Alloys ◽  
Room Temperature ◽  
Thermomechanical Processing ◽  
High Temperature Strength ◽  
Rapidly Solidified ◽  
Large Sheet ◽  
Room Temperature Strength

ABSTRACTIn recent years, interest in high temperature aluminum alloys has increased. However, nearly all the data available is for simple extrusions. This paper looks at the properties of sheet made from a rapidly solidified Al-10Fe-2.5V-2Si alloy. The sheet is made by direct forging followed by hot rolling, this is readily scalable, so allowing the production of large sheet. The room temperature strength and fracture toughness of the sheet are comparable to those of 2014-T6. The high temperature strength, specific stiffness and corrosion resistance are excellent. Recently, improved thermomechanical processing and new alloys have allowed higher strengths and fracture toughness values to be obtained.

Rapidly Solidified Ti Alloys Containing Metalloids and Rare Earth Metals— Their Microstructure and Mechanical Properties

1983 ◽  
Vol 28 ◽  
Author(s):  
C.S. Chi ◽  
S.H. Whang
Keyword(s):  
Rare Earth ◽  
Melt Spinning ◽  
Elevated Temperatures ◽  
Age Hardening ◽  
Second Phase ◽  
Precipitation Reaction ◽  
Strength Increase ◽  
Ti Alloys ◽  
Significant Difference ◽  
Rapidly Solidified

ABSTRACTRapidly solidified (RS) Ti alloys containing novel additives were prepared by splat quenching and melt spinning techniques. Microstructures of the as-quenched and heat-treated alloys were studied by electron microscopies. The results show that microstructural refinement and precipitation reaction are universal phenomena in all RS Ti alloys. A significant difference in second phase coarsening was observed between metalloid-origin precipitates and those of rare earth-origin. The precipitates in a Ti-Al-La(Ce) were identified predominantly as rare earth-Al compounds. Exce llent stability for rare earth-origin precipitates was found.Except for a carbon-containing alloy (700 ° C), age hardening behavior is a universal phenomenon in all RS Ti alloys with additives. A significant strength increase (hardness) in the RS alloy was noted at both room and elevated temperatures.

scholarly journals High pressure sintered ZrO2-6%wt REO

2007 ◽  
Vol 39 (1) ◽  
pp. 17-24
Author(s):  
C. Kuranaga ◽  
G.S. Bobrovnitchii
Keyword(s):  
Fracture Toughness ◽  
High Pressure ◽  
Rare Earth ◽  
High Temperature ◽  
Room Temperature ◽  
Rare Earth Oxide ◽  
Micro Hardness ◽  
Oxide Mixture ◽  
Sintering Conditions ◽  
High Temperature High Pressure

The sintering conditions employed in this work are innovative, due to the use of an alternative technology to process ZrO2-REO (rare earth oxide mixture), so called high temperature - high pressure (HPHT). A pressure of 5GPa was used, temperatures of 1100, 1200, and 1300 o C, for times of 2 and 5 minutes. The best results were obtained for samples sintered at 5GPa/1300 o C/5min., where a micro-hardness of 4.8GPa, fracture toughness of 5.3MPa.m ?, density of 97.9%, and 88% in volume of a tetragonal phase retained at room temperature were achieved.

Microstructures Development in Al-5Fe and Al-5Fe-3Y Alloys Solidified at Different Cooling Rate

2011 ◽  
Vol 189-193 ◽  
pp. 2462-2466
Author(s):  
Guo Fa Mi ◽  
Cui Fen Dong ◽  
Chang Yun Li ◽  
Hai Yan Wang
Keyword(s):  
Rare Earth ◽  
Phase Composition ◽  
Intermetallic Compound ◽  
Cooling Rate ◽  
Melt Spinning ◽  
Metastable Phase ◽  
Vacuum Melting ◽  
Suction Casting ◽  
Rapidly Solidified

Cast, sub-rapidly solidified and rapidly solidified Al-5Fe alloy and Al-5Fe-3Y alloy were respectively prepared by vacuum melting, suction casting and melt spinning. The effect of increasing cooling rate and adding rare earth Y alloy on microstructures and phase composition were investigated. The results showed that the acicular Al3Fe phase transferred to spherical phase and dispersed secondary precipitations were also found when 3.0 wt% Y was added in the Al-5Fe alloy. Meanwhile, the microstructures were apparently refined by the increasing of cooling rate. The metastable phase A16Fe and intermetallic compound A110Fe2Y phase have been observed in Al-5Fe alloy and Al-5Fe-3Y alloy, respectively.

The Effect of Heat Treatments on Microstructure and Creep Properties of Powder Metallurgy Beta Gamma Titanium Aluminide Alloys

2010 ◽  
Vol 654-656 ◽  
pp. 500-503 ◽  
Author(s):  
Trevor Sawatzky ◽  
Dong Yi Seo ◽  
H. Saari ◽  
D. Laurin ◽  
Dae Jin Kim ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Titanium Aluminide ◽  
Room Temperature ◽  
Tensile Creep ◽  
Air Cooling ◽  
Gamma Titanium Aluminide ◽  
Creep Properties ◽  
Gamma Titanium ◽  
Titanium Aluminide Alloys ◽  
Lamellar Interfaces

The microstructure and creep properties of two powder metallurgy (PM) ‘beta gamma’ titanium aluminide alloys are presented. Alloy powders with nominal compositions of TiAl-4Nb-3Mn (G1) and TiAl-2Nb-2Mo (G2) were produced by gas atomization and consolidated by a two-step hot isostatic pressing (HIP) process (1250 °C/200 MPa/1 hour + 1100 °C/200 MPa/3 hours + slow cooling to room temperature). After HIP, the materials were given a step cooled heat treatment (SCHT) of 40 min at 1400 °C, furnace cooling to 1280 °C, and air cooling to room temperature. Selected specimens were aged at 900 °C for 6 or 24 hours. The SCHT yielded similar fully lamellar microstructures for both alloys, with a lamellar spacing of 0.04 m, but with different grain sizes averaging 80 m (G1) and 40 m (G2). The aging treatments generated  precipitates along lamellar colony boundaries in both alloys, but along lamellar interfaces only in alloy G2. Constant load tensile creep tests were performed at 760 °C and 276 MPa. Alloy G2 exhibited superior creep performance compared to alloy G1, due to the quantity and size of  precipitate particles at the lamellar interfaces.

Effect of Different Cooling Speed and Rare Earth La on the Microstructures and Phase Constitution of Al-Fe Alloy

2010 ◽  
Vol 44-47 ◽  
pp. 2126-2130 ◽  
Author(s):  
Guo Fa Mi ◽  
Cui Fen Dong ◽  
Da Wei Zhao
Keyword(s):  
Rare Earth ◽  
Melt Spinning ◽  
Metastable Phase ◽  
Melting Furnace ◽  
High Melting Point ◽  
The Matrix ◽  
Cooling Speed ◽  
Matrix Morphology ◽  
Rapidly Solidified ◽  
Rare Earth La

The casting, sub-rapid solidified and rapidly solidified A1-5Fe alloys, with or without rare earth La have been respectively prepared by vacuum melting furnace, suction casting and melt spinning furnace. And the alloys were investigated with OM, TEM and XRD. The results show that the microstructure was apparently refined by the increasing of cooling rate. Meanwhile, the acicular Al3Fe phase transferred to flower-like phase in casting A1-5Fe alloy and the matrix morphology of the alloy also was changed in sub-rapidly solidified Al-5Fe alloy, while 1.5wt% La was added. The metastable phase A16Fe and Al11La3 phase with high melting point were found in Al-5Fe alloy and A1-5Fe-1.5La alloy.

Hot-Pressed Silicon Nitride Ceramics With Rare-Earth Oxides Additives

1985 ◽  
Author(s):  
Xu Youren ◽  
Huang Liping ◽  
Fu Xiren ◽  
Yen Tungsheng
Keyword(s):  
Fracture Toughness ◽  
Rare Earth ◽  
Silicon Nitride ◽  
Room Temperature ◽  
Glassy Phase ◽  
Rare Earth Oxides ◽  
Bend Strength ◽  
Silicon Nitride Ceramic ◽  
X Ray ◽  
Nitride Ceramics

A hot-pressed silicon nitride ceramic material with rare-earth oxides additive has been processed, its bend strength maintains 800–900 MPa up to 1300°C and measures 680 MPa at 1400°C, its fracture toughness at room temperature is 4.38–4.96 MPam. X-ray, SEM, EDS and electron probe analyses reveal that the microstructure of this material is composed of fine β-Si3N4 grains, α-Si3N4 whiskers, small tetragonal lanthanide crystals and La-containing glassy phase. Observation on fracture surface shows that the fracture path is mainly transcrystalline up to 1400°C. The effects of additives on strength and fracture toughness of HPSN obtained are also discussed.

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