Oxide Phase Formation in Excimer Laser Processed Ti Alloy

1991 ◽  
Vol 236 ◽  
Author(s):  
T. R. Jervis ◽  
K. M. Hubbard ◽  
T. G. Zocco
Keyword(s):  
Surface Layer ◽  
Excimer Laser ◽  
Single Pulse ◽  
Oxide Phase ◽  
Grain Structure ◽  
Ti Alloy ◽  
Fine Grained ◽  
Pulse Processing ◽  
Oxygen Incorporation ◽  
Oxide Phases

AbstractExcimer laser surface processing of Ti-6A1-4V results in substantial surface oxygen incorporation as measured by the narrow resonance in the elastic scattering of a particles at 3.05 MeV. Single pulse processing at 1.0 J-cm−2 results in transformation from the original a + β grain structure to a martensite structure. Multiple pulse processing results in oxygen incorporation proportional to the number of pulses during processing, but this is primarily reflected in the depth of the oxygen containing layer. A maximum oxygen to titanium ratio of 1.0 was observed in the surface layer. This was confirmed by transmission electron microscopy (TEM) which showed the development of a fine-grained equiaxed TiO surface layer from a phase mixture of Ti alloy with TiO precipitates. Concentration vs. depth profiles show that this layer is approximately 400 nm thick after 40 pulses. Further processing with a total of 60 pulses results in coarsening of the grains and an increase in the thickness of the layer. The TiO precipitate concentration increases gradually, becoming apparent in electron diffraction patterns after 30 pulses. No other oxide phases are observed, the TiO developing directly from the metallic phases. In particular, we do not observe the formation of Ti2O prior to the formation of the TiO, or the formation of TiO2.

Single pulse vibrational Raman scattering by a broadband KrF excimer laser in a hydrogen–air flame

1990 ◽  
Vol 29 (15) ◽  
pp. 2325 ◽  
Author(s):  
Robert W. Pitz ◽  
Joseph A. Wehrmeyer ◽  
J. M. Bowling ◽  
Tsarng-Sheng Cheng
Keyword(s):  
Raman Scattering ◽  
Excimer Laser ◽  
Single Pulse ◽  
Krf Excimer Laser

Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

2015 ◽  
Vol 324 ◽  
pp. 405-413 ◽  
Author(s):  
Jun-Hua Wang ◽  
Jin Wang ◽  
Yan Lu ◽  
Mao-Hua Du ◽  
Fu-Zhu Han
Keyword(s):  
Pulse Energy ◽  
Ceramic Coating ◽  
Single Pulse ◽  
Ti Alloy ◽  
Single Pulse Energy ◽  
Micro Arc Oxidation

Femtosecond Pulsed Laser-Induced Micromachining of Difficult-to-Machine Materials: Diamond a Case Study

2000 ◽  
Author(s):  
A. P. Malshe ◽  
A. M. Ozkan ◽  
T. A. Railkar ◽  
K. P. Adhi ◽  
W. D. Brown ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Excimer Laser ◽  
Etching Rate ◽  
Polycrystalline Diamond ◽  
Single Pulse ◽  
Laser Wavelength ◽  
Diamond Surface ◽  
Single Shot ◽  
Micro Machining ◽  
3 Dimensional

Abstract Meso and micro scale machining is an important and emerging area of research. Various non-traditional and novel tools are being explored for meso and micro machining of non-silicon materials. In this paper, we report etching, micro machining and related phenomena of commercially available single and polycrystalline diamond using a femtosecond pulsed excimer laser (λ = 248 nm, tp ∼ 380 fs). Surface modifications due to single pulse and multiple pulse irradiation of diamond samples, at different energy densities, have been analyzed using Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Etching rate of single crystal type IIA diamond by femtosecond pulsed excimer laser is also studied. Raman spectroscopy study of the single shot irradiation of diamond with a femto second laser shows the formation of a non-diamond disordered (sp2 bonded) phase on the surface. However, subsequent micro machining of this non-diamond disordered surface, by delivering several shots from the femtosecond laser, results in the removal of the non-diamond disordered layer and the restoration of the diamond surface. It is experimentally shown that the periodicity of the 2-dimensional corrugations written on diamond surface is shorter than the laser wavelength used. 3-dimensional writing on diamond globules during laser etching is also discussed. Further, micro machining of diamond tips is shown to be precise, and without mechanical and chemical damages. Femto second laser is demonstrated as a next-generation tool for mechanical and chemical damage free precision micro machining of the hardest material, diamond.

Development of Superplastic Properties in Quasi Single Phase Alloys

2007 ◽  
Vol 551-552 ◽  
pp. 357-364 ◽  
Author(s):  
Roger Grimes ◽  
R.J. Dashwood ◽  
A. Dorban ◽  
M. Jackson ◽  
S. Katsas ◽  
...  
Keyword(s):  
Single Phase ◽  
Early Stage ◽  
Strip Casting ◽  
Grain Structure ◽  
Freezing Range ◽  
Two Phase ◽  
Fine Grained ◽  
Cast Doubt ◽  
Recent Developments ◽  
Superplastic Properties

The early view of superplasticity was that it was a phenomenon that could only be exhibited by fine grained, two phase alloys. This effectively ruled out most alloys that possessed attractive service properties. The first material to demonstrate good superplastic properties from a virtually single phase microstructure was the Al-6%Cu-0.5%Zr, AA 2004 but this was followed by superplastic versions of AA7475, AA8090 and AA5083. Superplasticity was also demonstrated in magnesium based alloys at an early stage. More recently different grain control additions, such as scandium or erbium have been investigated and it has also been demonstrated that, in certain circumstances, aluminium simply with the addition of a grain controlling element can exhibit good superplastic behaviour. While conventional wisdom teaches that large fabricating strains are required to confer good superplastic properties in the sheet product, recent results with both aluminium and magnesium alloys cast doubt on this belief. Although, for many years, strip casting has appeared to provide an attractive semi-fabricating route for superplastic sheet problems with centre line segregation in alloys with a wide freezing range have precluded its use. It has been demonstrated that recent developments in strip casting enable production of alloys with as wide a freezing range as AA5182 to be cast with a fine, equiaxed grain structure across the strip thickness. The paper will review the state of these various developments and their implications for the manufacture of superplastic sheet materials.

Ultrafine Grain Structure Development in Aluminium Alloy by Strain Hardening using CCGP

2021 ◽  
Vol 1 (2) ◽  
pp. 25-31
Author(s):  
HS Siddesha ◽  
Suhaaskapardhi BS ◽  
Goutham C
Keyword(s):  
Tensile Strength ◽  
Aluminium Alloy ◽  
Research Work ◽  
Industrial Applications ◽  
Grain Structure ◽  
Ultrafine Grain ◽  
Fine Grained ◽  
Processed Material ◽  
Super Plastic ◽  
Ultrafine Grain Structure

Severe Plastic Deformation (SPD) processes are for developing ultrafine grained (UFG) structured materials for different Industrial applications. Cyclic Constrained Groove Pressing (CCGP) is a technique, produce fine grained structures in metallic sheets or plates in mass production. The objective of research work is to investigate the influence of CCGP processing on the super plastic behaviour of an Aluminium alloy. Samples in “ascast” materials processed by CCGP with as cast, 1, 2, 3 and 4 passes. Processed Material study for microhardness and Tensile strength mechanical properties test were done for different test specimens. Grain refinement, microhardness and Tensile strength increased with the number of CCGP passes.

Simulation of crystallization of the melt modified by nanoscale particles during laser treatment of a metal surface

2021 ◽  
Vol 1 ◽  
pp. 5-14
Author(s):  
V.N. Popov ◽  
Keyword(s):  
Numerical Simulation ◽  
Surface Layer ◽  
Stokes Equations ◽  
Solid Phase ◽  
Laser Action ◽  
Heat Removal ◽  
Boussinesq Approximation ◽  
Grain Structure ◽  
Homogeneous Distribution ◽  
Dissolved Carbon

A 2D mathematical model is proposed for the modification of an iron-based alloy with refractory nanosized particles. Numerical simulation of the processes during the modification of the surface layer of the substrate metal using the energy of a laser pulse has been carried out. Within the framework of the proposed model, the processes of heating and melting of metal on a substrate covered with a layer of nanosized refractory particles penetrating into the molten metal, convective heat transfer in the melt, and solidification after the end of the pulse are considered. Metal melting is considered in the Stefan approximation, and when the melt is cooled, the model of heterogeneous nucleation and subsequent crystallization is used. The fluid flow is described by the Navier-Stokes equations in the Boussinesq approximation. The distribution of nanoparticles in the melt is modeled by moving markers. Based on the results of calculations, the mode of pulsed laser action is determined, in which a flow is formed for a homogeneous distribution of particles of the modifying substance in the presence of a surfactant in the metal. The volume of the solid phase formed around the nucleus determines the size of the grain structure in the solidified alloy. The liquidus temperature changes depending on the concentration of dissolved carbon in the melt. In the numerical simulation of the solidification of the surface layer of the metal, it was found that the conditions of nucleation and crystallization differ significantly in the volume of the melt. It is determined that the duration of nucleation in a supercooled melt is several tens of microseconds. The maximum number of crystallization centers occurs in areas where heat removal occurs most rapidly. With the growth of the solid phase in the melt and the release of the latent heat of crystallization, the value of supercooling decreases, the nucleation stops and the number of formed crystallization centers does not change further. The distribution of the dispersion of the crystal structure over the volume of the melted metal is estimated. It was found that as the melt cools, sequential-volume crystallization occurs.

Multiple Pulse Irradiation Effects in Excimer Laser-Induced Crystallization of Amorphous Si Films

1993 ◽  
Vol 321 ◽  
Author(s):  
H. J. Kim ◽  
James S. Im
Keyword(s):  
Excimer Laser ◽  
Single Pulse ◽  
Pulse Irradiation ◽  
Multiple Pulse ◽  
Melting Phenomenon ◽  
Irradiation Energy ◽  
Crystallization Experiments ◽  
Amorphous Si ◽  
Si Films ◽  
Induced Crystallization

ABSTRACTWe have experimentally Investigated the effects that are associated with Multiple-pulse irradiation in the excimer laser processing of thin Si films on SiO2. Double-pulse irradiation experiments revealed results, which are consistent with that which is known from single-pulse crystallization experiments, and these experiments confirm the applicability of the transformation scenarios, which were derived from single pulse-induced crystallization experiments [1,2]. The results from the Multiple-pulse irradiation experiments clearly show that gradual and substantial grain enlargement can occur — and only occurs — when the irradiation energy density is close to but less than the level that is required to melt the film completely. Based on these findings, we argue that the grain enlargement effect is a near-complete melting phenomenon that is associated with polycrystalline Si films, and we present a grain boundary melting model to account for this phenomenon. A brief discussion on the apparent similarities and physical differences between the observed phenomenon and the solid state grain growth processes is provided herein.

Shear Pressing for Grain Refinement of Al-Mg-Li Sheet

2007 ◽  
Vol 546-549 ◽  
pp. 885-888
Author(s):  
Yu Xuan Du ◽  
Xin Ming Zhang ◽  
Ling Ying Ye ◽  
Zhi Hui Luo
Keyword(s):  
Shear Deformation ◽  
Grain Refinement ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Grain Refining ◽  
Metallic Materials ◽  
Inclined Plane ◽  
Fine Grained ◽  
Electron Backscatter ◽  
Backscatter Diffraction

A novel shear-deformation technique, named ‘shear pressing’ (SP), was developed for fabrication of plate-shaped fine grained metallic materials. The principle of SP is that a material is subjected to shear deformation by utilizing pressing with inclined plane dies. A micrometer order grain structure was obtained in an Al-Mg-Li alloy at strain of ε = -2.3 by utilizing this technique. The grain refinement sequences during pressing were examined by electron backscatter diffraction. The enhancement of grain refinement to the Al-Mg-Li alloy was compared with plane strain compression (PSC) at similar strains. The effect of the shear strain on the accelerated grain refining during compressing has been discussed.

scholarly journals Composite Magnetic Sorbents Based on Iron Oxides in Different Polymer Matrices: Comparison and Application for Removal of Strontium

Biomimetics ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 22 ◽  
Author(s):  
Andrei Egorin ◽  
Eduard Tokar ◽  
Anna Matskevich ◽  
Nikita Ivanov ◽  
Ivan Tkachenko ◽  
...  
Keyword(s):  
Composite Material ◽  
Iron Oxides ◽  
Cation Exchange Resin ◽  
Oxide Phase ◽  
Polymer Matrices ◽  
Magnetic Characteristics ◽  
X Ray Diffraction ◽  
Magnetic Sorbents ◽  
Host Materials ◽  
Oxide Phases

Introduction of magnetic nanoparticles into composite sorbents based on polymer matrices has received great attention due to the possibility of using cheap iron oxides and removing spent sorbents by means of magnetic separation. In the present paper, we discuss the problem of creating magnetic sorbents using two types of matrices as host materials: synthetic cation exchange resin and natural aminopolysaccharide chitosan. The possibilities of applying matrices for the in situ formation of oxide phases of a specified composition with the required content of an inorganic component in a composite material were estimated. The composition of the oxide phase formed in the composite material was studied, and particle sizes were evaluated by the method of X-ray diffraction analysis. Magnetic characteristics were investigated. Sorption characteristics with respect to strontium for the composites containing iron oxides were determined.

Surface modification of Al–Si alloy by excimer laser pulse processing

2016 ◽  
Vol 173 ◽  
pp. 192-199 ◽  
Author(s):  
S. Mahanty ◽  
Gouthama
Keyword(s):  
Surface Modification ◽  
Laser Pulse ◽  
Excimer Laser ◽  
Pulse Processing ◽  
Excimer Laser Pulse
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