Oxidation Behavior of Rh-xTi Refractory Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 721-724
Author(s):  
Rabindra Mahapatra ◽  
A.W. Davis
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Complex Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Refractory Alloys ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Xrd Techniques ◽  
Lower Oxidation

In this paper we report the oxidation behavior of Rh-xTi (x = 15 & 20 atomic percent) alloys isothermally exposed in air between 1000 and 1300 oC up to a period of 312 hours. The weight gain of arc-melted Rh-15Ti and Rh-20Ti alloys as a function of time was monitored. Results indicate that the oxidation resistance of Rh-15Ti and Rh-20Ti alloys at 1000 and 11000 C is similar to that of advanced nickel-base superalloys. However, these alloys show excellent oxidation resistance beyond the operational limit for nickel-base superalloys. Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) techniques were used to study the microstructure and morphology of the oxides. These alloys oxidize by forming TiO2 and Rh2O3 complex oxides. The Rh-20Ti alloys displayed lower oxidation resistance than Rh-15Ti alloys.

Oxidation Behavior of Aluminide Coated Ti-Al-Cr-Nb-Zr-Y Alloys at High Temperatures

2015 ◽  
Vol 227 ◽  
pp. 345-348 ◽  
Author(s):  
Eddy Basuki ◽  
Djoko Prajitno ◽  
Pawawoi
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Aluminide Coating ◽  
Diffraction Method ◽  
Complex Oxides ◽  
Intermetallic Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Interdiffusion Process ◽  
Pack Aluminizing

In this study the oxidation behavior of diffusion aluminide coating containing layers of TiAl3 and TiAl2, develop on a substrate of Zr-Y doped α2-Ti3Al/γ-TiAlCrNb intermetallic alloy using pack aluminizing method, was investigated isothermally at 800°C, 900°C, and 1000°C under atmospheric air pressure. The pack cementation was carried out at 850°C for 25 hours in a pack containing 20%-wt Al, 2%-wt NH4Cl, and 78%-wt Al2O3.The phases in the coatings and oxide layers were examined by optical and scanning electron microscopy as well as X-ray diffraction method, while chemical composition of the oxides and phases were examined with EDS attached on the SEM. The experimental results showed that the addition of Zr and Y increases the oxidation resistance of the coating by formation of complex oxides mainly of Al2O3 at the coating surfaces and sub-surface. Combination of oxidation and interdiffusion process cause transformation of TiAl3 layer to TiAl2 that decrease the oxidation resistance through the formation of TiO2 rod crystals on the junction between TiAl2 and Al2O3 in the outer layer.

Characterisation of the Structure of Single-Crystal Nickel-Base Superalloys

2010 ◽  
Vol 638-642 ◽  
pp. 2227-2232 ◽  
Author(s):  
Alexander Epishin ◽  
Thomas Link ◽  
Udo Brückner
Keyword(s):  
Single Crystal ◽  
Dendritic Structure ◽  
Experimental Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Kinetics Of ◽  
Morphology Changes ◽  
Sem Investigation

New experimental methods developed by the authors for characterisation of the structure of single-crystal nickel-base superalloys are presented: X-ray diffraction at defined areas of the dendritic structure, none destructive SEM investigation of ’-morphology changes for different creep stresses and times with one specimen, and high resolution SEM investigations of dislocations in the ’-interfaces. Application of these techniques allowed to obtain new results, e.g. about the mosaicity of dendritic subgrains, distribution of the ’-misfit within a single dendrite and kinetics of rafting during creep in the superalloy CMSX-4 in wide temperature and stress ranges.

Effects of SiC on Oxidation Behavior of ZrB2-Based Composites with MoSi2 and SiC Additives

2014 ◽  
Vol 602-603 ◽  
pp. 457-462 ◽  
Author(s):  
Shu Qi Guo
Keyword(s):  
Weight Gain ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Bulk Material ◽  
Sample Surface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scale Layer ◽  
Exposure Temperature ◽  
Reactive Mixture

In this study, oxidation behavior of ZrB2-MoSi2-SiC composite was investigated in the hot-pressed 5-20 vol% SiC-containing ZrB2-20 vol% MoSi2-based composites which were exposed to dry air between 1100°C and 1500°C up to 10 hours. The effects of SiC additive on the oxidation behavior were assessed. Experimental results showed that the weight gain due to oxidation exposure in air increased with increasing exposure temperature and exposure time. Parabolic oxidation behavior was observed for all the compositions composites. On the other hand, the weight gain decreased with increasing amount of SiC added. The addition of SiC improved the oxidation resistance of the composites, and the improvement was enhanced with increasing amount of SiC added. In addition, X-ray diffraction was used to identify major crystalline phases present in both the as-received and the post-oxidized composites. The oxidized sample surface was characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The microstructure of the post-oxidized composites consisted of two characteristic regions: oxidized reactive region and unreactive bulk material region. Furthermore, the oxidized reactive region divided into an outermost dense silica-rich scale layer and oxidized reactive mixture layer. The improvement of the oxidation resistance due to the addition of SiC is associated with the presence of the thicker dense outermost scale layer which inhibited inward diffusion of oxygen through it.

scholarly journals Isothermal Oxidation Behavior of Novel Al2O3 / NiCrAlY / Ti3Al System at 850�C

2020 ◽  
Vol 71 (5) ◽  
pp. 106-116
Author(s):  
Alexandra Banu ◽  
Alexandru Paraschiv ◽  
Simona Petrescu ◽  
Irina Atkinson ◽  
Elena Maria Anghel ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Mass Gain ◽  
Isothermal Oxidation ◽  
Thermal Barrier ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aerospace Applications

The novel Al2O3 / NiCrAlY /alfa2-Ti3Al system obtained by APS technique was tested against long (500h) isothermal oxidation at 850�C in air for prospective use in aerospace applications. EDX-SEM, X-ray diffraction (XRD) and Raman investigations were conducted to substantiate structural, textural and mass gain modifications underwent by the Al2O3 / NiCrAlY /alfa2-Ti3Al system in comparison with bare alfa2-Ti3Al and NiCrAlY /alfa2-Ti3Al system. Improved oxidation resistance of the double-coated system is based on moderate oxygen and thermal barrier role played by the mixture of delta - and alfa-Al2O3 present in the top ceramic coat.

scholarly journals Lattice Misfit of High Refractory Ruthenium Containing Nickel-Base Superalloys

2011 ◽  
Vol 278 ◽  
pp. 60-65 ◽  
Author(s):  
Steffen Neumeier ◽  
J. Ang ◽  
R.A. Hobbs ◽  
Catherine M.F. Rae ◽  
Howard J. Stone
Keyword(s):  
Lattice Misfit ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Coherency Stress ◽  
Matrix Lattice ◽  
Chemical Segregation ◽  
Nickel Base Superalloys ◽  
Nickel Base

The influence of Ru, Co, Mo and W on the lattice misfit of eight highly alloyed Re containing single crystal nickel-base superalloys was investigated. High resolution X-ray diffraction (XRD) was used to relate the elemental partitioning behavior and the Vegard coefficients of the elements under investigation to the measured lattice parameter of the  and  phase. The residual chemical segregation and especially the coherency stress-induced tetragonal distortion of the  matrix lattice in the high Mo containing alloys results in the observation of two different lattice parameters for the  matrix phase. This leads to three overlapping, but clearly distinguishable {002} X-ray reflections.

One Step Synthesis and Characterization of Zirconia-Graphene Composites

2012 ◽  
Vol 600 ◽  
pp. 174-177 ◽  
Author(s):  
Jian Fei Xia ◽  
Zong Hua Wang ◽  
Yan Zhi Xia ◽  
Fei Fei Zhang ◽  
Fu Qiang Zhu ◽  
...  
Keyword(s):  
Synthesis And Characterization ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Graphene Composite ◽  
Transmission Electron ◽  
One Step ◽  
Ft Ir ◽  
Xrd Techniques

Zirconia-graphene composite (ZrO2-G) has been successfully synthesized via decomposition of ZrOCl2•6H2O in a water-isopropanol system with dispersed graphene oxide (GO) utilizing Na2S as a precursor could enable the occurrence of the deposition of Zr4+ and the deoxygenation of GO at the same time. Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques were used to characterize the samples. It was found that graphene were fully coated with ZrO2, and the ZrO2 existing in tetragonal phase, which resulted in the formation of two-dimensional composite.

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