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.

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.

Rapidly solidified Al3Ti-base alloys containing Ni

1988 ◽  
Vol 3 (1) ◽  
pp. 1-7 ◽  
Author(s):  
S. C. Huang ◽  
E. L. Hall ◽  
M. F. X. Gigliotti
Keyword(s):  
Melt Spinning ◽  
Single Phase ◽  
Analytical Electron Microscopy ◽  
Primary Phase ◽  
Second Phase ◽  
Equilibrium Conditions ◽  
Second Phase Particles ◽  
Analytical Electron ◽  
Wheel Side ◽  
Rapidly Solidified

Two Ni-modified Al3Ti alloys (Al65Ni10Ti25 and Al62Ni8Ti30) were rapidly solidified by melt spinning. The resulting microstructure was studied using light microscopy and analytical electron microscopy. Significant variations in the microstructure and phases were observed between the two ribbons and through the thickness of each ribbon.A single-phase γ-TiAl structure was seen near the wheel side of the Al62Ni8Ti30 ribbon, having microcrystalline grains ∼ 100 nm in diameter. Second-phase particles of Λ-AlNiTi were found in the remaining regions of that ribbon as the structure became columnar due to reduced rates of cooling. The Al65Ni10Ti25 alloy exhibited a primary phase of π-Al6.5 NiTi2.5. A second phase of μ-Al2NiTi formed with morphology and distribution varying through thickness. Microchemistry measurements on the phases indicated substantial deviations (up to 14 at. %) from the stoichiometric compositions. Further, the π, γ, and μ are low-temperature phases that do not form by solidification under equilibrium conditions. The observation of these phases thus suggests significant undercoolings achieved during the melt-spinning processing of the present alloys. Both ribbons are brittle as spun.

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.

Microstructural evaluation of a rapidly solidified Ti alloy containing Er and B

1984 ◽  
Vol 42 ◽  
pp. 504-505
Author(s):  
E. F. Koch ◽  
R. G. Rowe
Keyword(s):  
Rare Earth ◽  
Titanium Alloys ◽  
Density Ratio ◽  
Analytical Electron Microscopy ◽  
High Strength ◽  
Rare Earth Oxide ◽  
Maximum Temperature ◽  
Dispersion Strengthening ◽  
Microstructural Evaluation ◽  
Rapidly Solidified

The high strength to density ratio of titanium alloys make them ideal for applications where weight and moderate temperature resistance are critical. The maximum temperature for use of state of the art titanium alloys which are solid solution strengthened is on the order of 1000-1100°F. The chemical stability of most precipitate phases has been shown to be inadequate for the precipitaion strengthening of titanium alloys in this temperature range. Recently, it has been shown that alloying with rare earth elements combined with rapid solidification from the melt can produce stable rare earth oxide dis-persoids which have the potential for dispersion strengthening, and thus increase the high temperature capabilities of titanium alloys. In this paper, we describe the microstructural evaluation using analytical electron microscopy of rapidly-solidified filaments of titanium alloys containing rare earth and boron additions.

An Analytical Electron Microscopy Characterization of Melt-Spun Iron/Rare-Earth/Boron Magnetic Materials

1985 ◽  
Vol 58 ◽  
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless ◽  
G.C. Hadjiipanayis
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Rare Earth ◽  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
High Energy ◽  
Ion Milling ◽  
Analytical Electron ◽  
Strategic Element ◽  
Microscopy Characterization

Iron/rare-earth/boron permanent magnet materials have recently been delveloped to reduce the need for the strategic element cobalt, which was previously the primary canponent of high-energy magnets. These materials are generally produced by annealing rapidly solidified ribbons or by conventional powder metallurgy techniques. This paper will report results from an analytical electron microscopy characterization undertaken to establish the relationship between the magnetic properties and the microstructure of two iron/rare-earth/boron (Fe/RE/B) alloys. Ribbons of Fe75Pr15B10 and Fe77Tb15B8 were produced by melt-spinning. To obtain optimum magnetic properties, both alloys were then annealed at 700°C, the FePrB ribbons for 6 minutes and the FeTbB ribbons for 90 minutes. Foils for transmission electron microscopy were prepared by ion-milling the ribbons on a cold stage and examined using a Philips 400T TEM/STEM equipped with an energy dispersive x-ray unit.

Phase identification in SiC whisker reinforced Al2O3-R2O3-based composites

1992 ◽  
Vol 50 (1) ◽  
pp. 152-153
Author(s):  
C.M. Sung ◽  
K.J. Ostreicher ◽  
M.L. Huckabee ◽  
S.T. Buljan
Keyword(s):  
Analytical Electron Microscopy ◽  
Phase Identification ◽  
Reinforced Composites ◽  
Ion Milling ◽  
X Ray ◽  
Binary Oxides ◽  
Analytical Electron ◽  
The Matrix ◽  
Second Phases ◽  
Convergent Beam

A series of binary oxides and SiC whisker reinforced composites both having a matrix composed of an α-(Al, R)2O3 solid solution (R: rare earth) have been studied by analytical electron microscopy (AEM). The mechanical properties of the composites as well as crystal structure, composition, and defects of both second phases and the matrix were investigated. The formation of various second phases, e.g. garnet, β-Alumina, or perovskite structures in the binary Al2O3-R2O3 and the ternary Al2O3-R2O3-SiC(w) systems are discussed.Sections of the materials having thicknesses of 100 μm - 300 μm were first diamond core drilled. The discs were then polished and dimpled. The final step was ion milling with Ar+ until breakthrough occurred. Samples prepared in this manner were then analyzed using the Philips EM400T AEM. The low-Z energy dispersive X-ray spectroscopy (EDXS) data were obtained and correlated with convergent beam electron diffraction (CBED) patterns to identify phase compositions and structures. The following EDXS parameters were maintained in the analyzed areas: accelerating voltage of 120 keV, sample tilt of 12° and 20% dead time.

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.

AEM of a Ag-Y-Ba-Cu superconductor precursor material

1993 ◽  
Vol 51 ◽  
pp. 1192-1193
Author(s):  
A. J. Strutt ◽  
M. T. Simnad ◽  
E. Lavernia ◽  
K. S. Vecchio
Keyword(s):  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
Oxide Phase ◽  
Metallic State ◽  
Ion Milling ◽  
X Ray ◽  
Cu Alloy ◽  
Precursor Material ◽  
Analytical Electron ◽  
Spinning Process

Analytical electron microscopy (AEM) has been used to characterize a Ag-rich superconductor precursor material whose composition (before oxidation) was based on 10 wt.% of a YBa2Cu3 alloy and 90 wt.% Ag, and the same material after an oxidation heat treatment of 690°C for 24 hours. The material had been produced by a melt spinning process as a metallic alloy to permit deformation of the material (in the metallic state) prior to subsequent oxidation to form the ceramic superconducting Y-Ba-Cu oxide phase.The microstructure was characterized using a Philips CM30 AEM, at 300 kV, using specimens thinned to electron transparency by ion-milling. Energy dispersive X-ray spectroscopy (EDX) was performed using the same instrument, with a Link Analytical solid-state X-ray detector with an ultra-thin window.In the as-formed condition, the Y-Ba-Cu alloy phase exists as discrete particles at the triple points of the relatively fine (approx. 250 nm.)

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.

scholarly journals Formation mechanisms and atomic configurations of nitride phases at the interface of aluminum nitride and titanium

2008 ◽  
Vol 23 (8) ◽  
pp. 2221-2228 ◽  
Author(s):  
Chia-Hsiang Chiu ◽  
Chien-Cheng Lin
Keyword(s):  
Electron Microscopy ◽  
Aluminum Nitride ◽  
Analytical Electron Microscopy ◽  
Phase Region ◽  
Titanium Foil ◽  
Formation Mechanisms ◽  
Two Phase ◽  
Analytical Electron ◽  
The Matrix ◽  
Lamellar Layer

Aluminum nitride was bonded with a titanium foil at 1400 °C for up to 1 h in Ar. The AlN/Ti interfacial reactions were investigated using analytical electron microscopy. Reaction layers, consisting of δ-TiN, τ2-Ti2AlN, γ-TiAl, α2-Ti3Al, a two-phase region (α2-Ti3Al + α-Ti), and α-Ti (Al, N) solid solution, were observed after annealing at 1400 °C for 0.1 h. Among these phases, the α2-Ti3Al and (α2-Ti3Al + α-Ti) were formed during cooling. Further diffusion of N atoms into the reaction zone precipitates a chopped fiber-like α2-Ti2AlN in the matrix of γ-TiAl, with [110]γ−TiAl//[11¯20]τ2−Ti2AlN and (1¯1¯1)γ−TiAl//(1¯10¯3)τ2−Ti2AlN, by substituting N atoms for one-half Al atoms after annealing at 1400 °C for 1 h. The released Al atoms, due to the precipitation of τ2-Ti2AlN, resulted in an ordered Al-rich γ-TiAl or Ti3Al5. Furthermore, the α-Ti (Al, N) was nitridized into a lamellar layer (δ-TiN + α-Ti) with [110]δ−TiN//[11¯20]α−Ti and (111)δ−TiN//(0001)α−Ti.

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