Metastable phase evolution in Al2O3 dispersed nanocrystalline NiCr alloys

2007 ◽  
Vol 22 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Dheepa Srinivasan ◽  
P.R. Subramanian
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Grain Growth ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Metastable Phase ◽  
Phase Evolution ◽  
Free Energies ◽  
Alumina Particles ◽  
The Matrix

The high temperature structural stability of nanograined NiCr alloys reinforced with nanoscale yttria and alumina dispersoids, fabricated by electron beam physical vapor deposition (EBPVD), was examined. The yttria particles coarsened very little and also inhibited grain growth in the matrix successfully, whereas the alumina dispersoids coarsened rapidly and were not as effective in restricting matrix grain growth. A hierarchy of phase transformations took place in the Al2O3 particles present as nano dispersoids in a nanograined NiCr matrix , on annealing. Coarsening of the alumina particles was accompanied by these phase transitions. The phase evolution is attributed to differences in free energies between the metastable and stable phases and a kinetic hierarchy in nucleation, brought about by structural and hence interfacial energy considerations.

Strain Tolerance and Microstructure of Thermal Barrier Coatings Produced by Electron Beam Physical Vapor Deposition Process

2006 ◽  
Vol 522-523 ◽  
pp. 267-276 ◽  
Author(s):  
Kunihiko Wada ◽  
Yutaka Ishiwata ◽  
Norio Yamaguchi ◽  
Hideaki Matsubara
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Thermal Barrier Coatings ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Aging Treatment ◽  
Nanoindentation Test ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Strain Tolerance

Several kinds of thermal barrier coatings (TBCs) deposited by electron beam physical vapor deposition (EB-PVD) were produced as a function of electron beam power in order to evaluate their strain tolerance. The deposition temperatures were changed from 1210 K to 1303 K depending on EB power. In order to evaluate strain tolerances of the EB-PVD/TBCs, a uniaxial compressive spallation test was newly proposed in this study. In addition, the microstructures of the layers were observed with SEM and Young’s moduli were measured by a nanoindentation test. The strain tolerance in as-deposited samples decreased with an increase in deposition temperature. In the sample deposited at 1210 and 1268 K, high-temperature aging treatment at 1273 K for 10 h remarkably promoted the reduction of the strain tolerance. The growth of thermally grown oxide (TGO) layer generated at the interface between topcoat and bondcoat layers was the principal reason for this strain tolerance reduction. We observed TGO-layer growth even in the as-deposited sample. Although the thickness of the initial TGO layer in the sample deposited at high temperature was thicker, the growth rate during aging treatment was smaller than those of the other specimens. This result suggests that we can improve the oxidation resistance of TBC systems by controlling the processing parameters in the EB-PVD process.

Intermetallic Matrix Composites by Physical Vapor Deposition

1990 ◽  
Vol 194 ◽  
Author(s):  
Dallis A. Hardwick ◽  
Richard C. Cordi
Keyword(s):  
Electron Beam ◽  
Cross Sections ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Sheet Material ◽  
Electron Beam Evaporation ◽  
Layered Composite ◽  
Auger Analysis ◽  
The Matrix ◽  
Intermetallic Matrix Composites

AbstractThe feasibility of producing layered composite sheet material, in which the matrix is the intermetallic compound TiAl, using physical vapor deposition (PVD) has been demonstrated. The PVD techniques of sputtering and electron beam evaporation were both investigated. Films were deposited by alternately sputtering from targets of composition Ti-53A1–3Nb and TiB2 or were co-deposited from separate electron beam heated hearths containing Ti and Al. In the latter case, nitrogen gas was pulsed into the deposition chamber at controlled intervals resulting in the formation of a TiAl/TiAlN layered composite. The composition of the films was determined using Auger analysis and Rutherford backscattering spectroscopy and the crystal structure was checked using X-ray and electron diffraction. Cross-sections through the films were prepared for examination by transmission electron microscopy so that the layered microstructure of the films could be verified.

Comparison of Electron-Beam Physical Vapor Deposition and Plasma-Spray Physical Vapor Deposition Thermal Barrier Coating Properties Using Synchrotron X-Ray Diffraction

2019 ◽  
Author(s):  
Matthew Northam ◽  
Lin Rossmann ◽  
Brooke Sarley ◽  
Bryan Harder ◽  
Jun-Sang Park ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Plasma Spray ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Thermal Barrier ◽  
Jet Engines ◽  
X Ray Diffraction ◽  
X Ray

Abstract Electron-beam physical vapor deposition (EB-PVD) is widely used for the application of thermal barrier coatings (TBCs) to turbine blades in jet engines. An emerging method, plasma-spray physical vapor deposition (PS-PVD), is a hybrid technique whereby coatings can be applied via the liquid phase to form lamellar microstructures or via the vapor to form columnar microstructures similar to that of EB-PVD. In this study, PS-PVD and conventional EB-PVD coated samples of a columnar configuration were prepared and thermally cycled to 300 and 600 cycles. These samples were subsequently characterized in-situ, under thermal load using synchrotron x-rays. From the high-resolution x-ray diffraction (XRD) patterns, the residual and in-situ strain in the TGO layer was obtained during a thermal cycle. At high temperature, the TGO layer for both deposition methods displayed a constant near zero-strain for all samples as anticipated. In the samples with 300 thermal cycles, both deposition methods showed similar strain profiles in the TGO layer. For samples with 600 cycles, PS-PVD samples showed a more significant strain relief in the TGO at room temperature compared to similarly cycled EB-PVD samples. This could explain the coating lifetime performance between the two deposition methods. The findings support ongoing efforts to tune the manufacturing of PS-PVD coatings towards the goal of meeting or exceeding the performance of currently used coatings on jet engines. This will pave the way for more affordable high temperature coating alternatives that meet durability needs.

Preparation of a dense ytterbium disilicate layer via dual electron beam physical vapor deposition at high temperature

2017 ◽  
Vol 193 ◽  
pp. 176-178 ◽  
Author(s):  
Taishi Yokoi ◽  
Norio Yamaguchi ◽  
Makoto Tanaka ◽  
Daisaku Yokoe ◽  
Takeharu Kato ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Vapor Deposition ◽  
Physical Vapor Deposition
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