Interfacial Reactions of Ti-24Al-11Nb Alloy with Al2O3

1993 ◽  
Vol 318 ◽  
Author(s):  
Weimin Si ◽  
Pengxing Li ◽  
Renjie Wu
Keyword(s):  
Interfacial Reactions ◽  
Diffusion Couples ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Interfacial Layers ◽  
Free Zone ◽  
Β Phase ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Reaction Zones

ABSTRACTThe interfacial reactions and interdiffusion between Al2O3 and Ti-24Al-11Nb (at%) alloy have been investigated. Diffusion couples were fabricated by thermal sprayed Al2O3 film onto Ti-24Al-11Nb substrate, and then annealed at 1200°C. Interfacial layers were characterized using electron probe microanalysis (EPMA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The layered structure of interface region was observed which showed the diffusion controlled characteristics. In the reaction zones, the reaction products consisted mainly of TiO, TiO2, and Al2TiO5. Adjacent to the reaction zones, there existed β phase free zone and β phase lacking zone. The β phase free zone resulted from Nb depletion of this region. The reaction mechanism has been discussed using thermodynamic approach.

Interfacial reactions between Y1Ba2Cu3O7−x and Ag–Pd alloys during high temperature heat treatments

1992 ◽  
Vol 7 (11) ◽  
pp. 2936-2941 ◽  
Author(s):  
R. Allem ◽  
F. Lavallée ◽  
G. L'Espérance ◽  
R. Schulz ◽  
M.L. Trudeau
Keyword(s):  
Melting Point ◽  
Auger Spectroscopy ◽  
Heat Treatments ◽  
Interfacial Reactions ◽  
Cubic Phase ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Ag Particles

The interfacial reactions between the Y1Ba2Cu3O7−x (123) compound and a Ag70Pd30 alloy have been studied for several heat treatments below and above the melting point of the superconductor. Scanning and transmission electron microscopy, energy dispersive x-ray analysis, Auger spectroscopy, and x-ray diffraction have been used to characterize the reaction products. For the heat treatments below the melting point of the superconductor (950 °C), the Ba and Cu of the 123 compound migrate to the interface and react with the Pd to form a body-centered cubic phase Ba(Pd, Cu)O2. This structure is formed by substitution of Cu by Pd on the Cu+2 sites of the BaCuO2 structure (Im3m space group). CuO is also found in some areas as a product of the reaction. For the thermal treatments above the melting point of the superconductor, the reaction products are the same but, in this case, a large number of Y2BaCuO5 precipitates are found in the bulk of the superconductor near the interface. Pure Ag particles have also been observed in the 123 compound at distances relatively far from the interface.

Interfacial Compatibility of Ti3Al with Various Ceramic Reinforcements

1993 ◽  
Vol 318 ◽  
Author(s):  
Weimin Si ◽  
Pengxing Li ◽  
Renjie Wu
Keyword(s):  
Interfacial Layer ◽  
Depth Profiling ◽  
Kinetic Studies ◽  
Diffusion Couples ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Interfacial Compatibility ◽  
Reaction Zones ◽  
Thin Film Diffusion ◽  
Ti3al Alloy

ABSTRACTThe interfacial compatibility of SiC, Al2O3, and TiC with Ti3Al alloy has been evaluated. Thin films of these three ceramics materials were deposited on Ti3A1 substrates. The thin film diffusion couples were annealed from 600°C to 1000°C, and the thickness of the interfacial layer was obtained from Auger Electron Spectroscopy (AES) concentration depth profiling. The reaction products were identified by X-ray Diffraction (XRD) and AES. In the A12O3/Ti3A1, obvious interdiffusion occurred with some reaction products. In the SiC/Ti3Al, significant interdiffusion and reactions occurred in the interfacial layer, and multilayer reaction zones were found. In the TiC/Ti3Al, the reaction product was primarily the P(Ti3AlC) phase. Kinetic studies of the growth of the interfacial layer showed that SiC reacted most severely with Ti3Al, TiC less so, and AI2O3 the least. The compatibility of these three systems has been assessed.

A TEM investigation of a hyper-eutectic lead-tin alloy

1988 ◽  
Vol 46 ◽  
pp. 562-563
Author(s):  
John A. Sutliff
Keyword(s):  
Volume Diffusion ◽  
Eutectic Mixture ◽  
Precipitation Reaction ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Discontinuous Precipitation Reaction ◽  
Controlled Precipitation

Near-eutectic Pb-Sn alloys are important solders used by the electronics industry. In these solders, the eutectic mixture, which solidifies last, is the important microstructural consituent. The orientation relation (OR) between the eutectic phases has previously been determined for directionally solidified (DS) eutectic alloys using x-ray diffraction or electron chanelling techniques. In the present investigation the microstructure of a conventionally cast, hyper-eutectic Pb-Sn alloy was examined by transmission electron microscopy (TEM) and the OR between the eutectic phases was determined by electron diffraction. Precipitates of Sn in Pb were also observed and the OR determined. The same OR was found in both the eutectic and precipitation reacted materials. While the precipitation of Sn in Pb was previously shown to occur by a discontinuous precipitation reaction,3 the present work confirms a recent finding that volume diffusion controlled precipitation can also occur.Samples that are representative of the solder's cast microstructure are difficult to prepare for TEM because the alloy is multiphase and the phases are soft.

Influence of Quenching Rates on the Transformation of Ternary Phases in Nb-rich γ-TiAl Alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Andreas Stark ◽  
Michael Oehring ◽  
Florian Pyczak
Keyword(s):  
Elevated Temperatures ◽  
High Energy ◽  
X Ray Diffraction ◽  
Quenching Rate ◽  
Repeated Heating ◽  
Β Phase ◽  
Third Phase ◽  
Diffusion Controlled ◽  
Temperature Ramp ◽  
Ordered Phases

ABSTRACTIntermetallic γ-TiAl based alloys with additional amounts of the ternary bcc β phase attracted increasing attention in recent years due to their improved workability at elevated temperatures. At lower temperatures the ductile high-temperature β phase can transform to several ordered phases. However, actually available phase diagrams of these multiphase alloys are quite uncertain and the precipitation kinetics of some metastable phases is far from understood.In the present study various transformations of the third phase are observed in situ by means of high-energy x-ray diffraction using synchrotron radiation. A Ti-45Al-10Nb (at.%) specimen is subject to a temperature ramp of repeated heating cycles (700 °C - 1100 °C) with subsequent quenching at different rates. Depending on the quenching rate reversible transformations of the B2-ordered βo phase to different ω related phases are observed in Ti-45Al-10Nb. At low quenching rates the hexagonal B82-ordered ωo phase is formed while at high quenching rates the metastable intermediate trigonal ω’’ phase can be preserved. The results indicate that the complete transformation from βo to hexagonal B82-ordered ωo consists of two steps which are both diffusion controlled.

Microstructure and Shape Memory Behavior of Ti-18Nb-6Zr (at.%) Alloy

2021 ◽  
Vol 1016 ◽  
pp. 1368-1373
Author(s):  
Xiao Yun Song ◽  
Wen Jun Ye ◽  
Song Xiao Hui
Keyword(s):  
Shape Memory ◽  
Tensile Deformation ◽  
Solution Treatment ◽  
Tensile Tests ◽  
Martensite Phase ◽  
Air Cooling ◽  
X Ray Diffraction ◽  
Β Phase ◽  
Transmission Electron ◽  
Cold Rolled

The microstructures and shape memory behaviors of Ti-18Nb-6Zr (at.%) alloy subjected to different heat treatments were investigated through optical microscopy (OM), X-ray diffraction (XRD), Transmission electron microscopy (TEM) and tensile tests. Recrystallization occurs in cold-rolled Ti-18Nb-6Zr alloy after solution treatment at 600~800 °C. The cooling rate after solution treatment at 800°C shows a dramatic effect on the microstructure of the alloy. The microstructures for the water quenching (WQ) and oil quenching (OQ) specimens are composed of single α'' martensite phase, while for the air cooling (AC) specimen, the microstructure consists of predominant β phase and a small amount of fine athermal ω phase. During tensile deformation, two-stage yielding is observed in the alloy subjected to 800°C/0.5h/WQ heat treatment. The stress for martensite variants reorientation and the yield stress for plastic deformation are 310MPa and 455MPa, respectievely, and the maximum shape memory strain of 3.1% is obtained with pre-strain of 6%.

Effects of Thermo-Mechanical Treatment on the Microstructure of AA7085 Aluminum Alloy

2014 ◽  
Vol 794-796 ◽  
pp. 1193-1198 ◽  
Author(s):  
Hong Wei Tong ◽  
Wen Yi Liu ◽  
Guang Jie Huang ◽  
Qing Liu
Keyword(s):  
Electron Microscopy ◽  
Rolled Plate ◽  
X Ray Diffraction ◽  
Warm Deformation ◽  
X Ray ◽  
Free Zone ◽  
Transmission Electron ◽  
Hardness Tests ◽  
Continuous Chain

The microstructure of pre-aged AA7085 rolled plate was studied by means of hardness tests, optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and electrical conductivity tests. The results show that supper refined and homogeneous precipitates were formed during pre-aging, but the hardness of the alloy was still relatively low. There occurred a large number of dislocations when the warm deformation was introduced, and the size of the intragranular precipitates firstly increases and then decreases and then increases with the dislocation density increasing, which was caused by the role of dislocations on inhibiting the formation of GP zone and promoting the nucleation and transformation ofηphase. Meanwhile, the distribution of grain boundary precipitates also changed from continuous chain to coarsening interrupted distribution and the precipitate free zone (PFZ) broadened obviously.

Stable Pt/Ge/Au Ohmic Contact to N-GaAs with a Ta-Si-N Barrier

1993 ◽  
Vol 300 ◽  
Author(s):  
J. S. Chen ◽  
E. Kolawa ◽  
R. P. Ruiz ◽  
M-A. Nicolet
Keyword(s):  
Barrier Layer ◽  
Main Reaction ◽  
X Rays ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Semiconductor Interface ◽  
Rich Phase ◽  
X Ray ◽  
Thermal Reactions ◽  
Transmission Electron

ABSTRACTA Pt/Ge/Au contact of the structure: <n-GaAs>/Pt(17nm)/Ge(25nm)/Au(43nm), overlaid with a Ta-Si-N barrier layer and a Au metallization layer has a contact resistivity, ρc, of 3.7×10−6 Ωcm2 after annealing at 450°C for 15 min. After aging at 450°C for 60 h, ρc slightly degrades to 5.5×10−6 Ωcm2 while the surface keeps smooth. When alloyed at 550°C for 15 min, ρc is 1.8×10−6 Ωcm2 and stays about the same value after annealing at 550°C for 1 h. Without the Ta-Si-N barrier and the Au overlayer, the Pt/Ge/Au contact alone is also ohmic after annealing at 450°C for 15 min but with a ρc of ∼10−5 Ωcm2 while the surface morphology deteriorates significantly after aging at 450°C for 20 h.The thermal reactions of this Pt/Ge/Au contact on GaAs, with or without a Ta-Si-N barrier layer, are investigated by backscattering spectrometry, x-ray diffraction, and transmission electron microscopy in conjunction with energy dispersive analyses of x-rays. For all samples, the main reaction products after annealing at 450°C for 15 min are Au7Ga2, and PtGe:As, a PtGe phase that also contains arsenic. The product phases are randomly distributed within a laterally uniform reacted layer when the Pt/Ge/Au contact is covered by a Ta-Si-N layer. Without the Ta-Si-N barrier layer, a small arsenic loss and a Ga-rich phase (probably Gaoxides) on the contact surface are observed after annealing at 450°C. In this case, the surface and contact-semiconductor interface are more faceted than with a Ta-Si-N barrier layer.

Effect of Hot Swaging on Microstructure and Properties of Aged Ti-10Mo-20Nb Alloy

2016 ◽  
Vol 869 ◽  
pp. 952-956 ◽  
Author(s):  
Sinara Borborema Gabriel ◽  
Jean Dille ◽  
Carlos Angelo Nunes ◽  
Emanuel Santos Jr. ◽  
Renato Baldan ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Biomedical Applications ◽  
Thermomechanical Processing ◽  
Young's Modulus ◽  
Stress Shielding ◽  
X Ray Diffraction ◽  
High Mechanical Strength ◽  
Β Phase ◽  
Transmission Electron ◽  
Final Microstructure

Mechanical properties of metastable β-Ti alloys are highly dependent on the final microstructure, which is controlled by the thermomechanical processing. These alloys are used for biomedical applications and require a high mechanical strength as well as a low Young’s modulus to avoid stress shielding. Previous work on the development of cold swaged Ti-10Mo-20Nb alloy showed that the best compromise strength and Young ́s modulus was obtained when the forming is followed by an aging heat treatment at 500 oC. In this work, Ti-10Mo-20Nb alloy was hot swaged and aged at 500 oC for 10 min, 4h and 24h. The microstructure was analyzed by X-ray diffraction, optical microscopy and transmission electron microscopy. Mechanical characterization was based on Vickers microhardness tests and Young’s modulus measurements. Aging at 500 oC for 10 min after hot swaging resulted in a nearly 100% β phase microstructure while aging at 500°C for 4h or 24h led to a bimodal microstructure consisting on α precipitates dispersed in the β matrix. The higher hardness to Young’s modulus ratio was obtained for the sample aged at 500 °C for 4h. This value was higher than those obtained for the Ti-6Al-4V alloy and commercially pure Ti.

Functionalized Silicate Supported TiO2-ZnO Nanocomposite Film and its Application in Simultaneous Photocatalytic Degradation of Toxic Molecules

2013 ◽  
Vol 764 ◽  
pp. 255-265 ◽  
Author(s):  
R. Dhanalakshmi ◽  
A. Pandikumar ◽  
R. Ramaraj
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Potential Candidate ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
Molar Ratios ◽  
Amine Functionalized ◽  
Transmission Electron

The TiO2-ZnO nanocomposite materials ((TiO2-ZnO)NCM) with different molar ratios (Ti:Zn) was synthesized by chemical route and dispersed in functionalized silicate sol-gel matrix (Silicate/(TiO2-ZnO)NCM)). The as prepared Silicate/(TiO2-ZnO)NCM were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The dispersion of the small amount of (TiO2-ZnO)NCM in silicate sol-gel matrix paves the way for the preparation of solid-state thin film photocatalyst which is advantageous for the separation of the catalyst from solution, the substrates and the reaction products. The simultaneous photoinduced oxidation of methylene blue (MB) dye and reduction of Cr (VI) to Cr (III) was examined at different amine functionalized silicate sol-gel embedded (TiO2-ZnO)NCM films. The (TiO2-ZnO)NCM dispersed into the amine functionalized silicate sol-gel matrix (TPDT) exhibited enhanced photocatalytic activity when compared to the (TiO2-ZnO)NCM without the silicate sol-gel. The functionalized silicate sol-gel supported (TiO2-ZnO)NCM is a potential candidate for energy conversion and environment remediation and cleaning applications.

Microstructural Evaluation of Boron Free and Boron Containing Heat-Treated Ti-35Nb-7.2Zr-5.7Ta Alloy

2012 ◽  
Vol 18 (2) ◽  
pp. 295-303 ◽  
Author(s):  
Pallab Majumdar
Keyword(s):  
X Ray Diffraction ◽  
Second Stage ◽  
Β Phase ◽  
Solution Treated ◽  
Α Phase ◽  
Treatment Conditions ◽  
Transmission Electron ◽  
Heat Treated ◽  
Microstructural Evaluation ◽  
Diffraction Patterns

AbstractThe microstructure of Ti-35Nb-7.2Zr-5.7Ta (TNZT) and Ti-35Nb-7.2Zr-5.7Ta-0.5B (TNZTB) alloys under different heat treatment conditions has been analyzed. The solution-treated and water-quenched TNZT sample consists mainly of β phase with a very small amount of fine athermal ω precipitate. Precipitation of α can be observed when solution-treated samples are directly aged at 580°C for 8 h. The microstructure of the samples subjected to single-stage aging at 300°C or 400°C consists of ω precipitates in equiaxed β grains. Second stage aging at 580°C for 8 h after first stage of aging at 300°C or 400°C results in the replacement of ω precipitates by secondary α. In all of these samples, the amount of ω or α phase was very small, and therefore they could not be detected by X-ray diffraction studies. However, analysis of selected area diffraction patterns obtained from transmission electron microscopy studies confirms their presence. The addition of boron leads to the formation of dispersed precipitates of TiB in the β matrix of the TNZT alloy and also refines the β grains in the microstructure. However, other microstructural features of the TNZTB alloy are similar to those of the TNZT alloy.

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