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Materials Engineering

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Articles 361 - 380 of 380

Full-Text Articles in Engineering

Orientation Relationships In The System Nb-Nbcr2, P. G. Kotula, Katherine C. Chen, Dan J. Thoma, F. Chu, T. E. Mitchell Aug 1997

Orientation Relationships In The System Nb-Nbcr2, P. G. Kotula, Katherine C. Chen, Dan J. Thoma, F. Chu, T. E. Mitchell

Materials Engineering

No abstract provided.


Assessment Of The Compositional Influences On The Toughness Of Ticr2-Base Laves Phase Alloys, Katherine C. Chen, Samuel M. Allen, James D. Livingston Jan 1996

Assessment Of The Compositional Influences On The Toughness Of Ticr2-Base Laves Phase Alloys, Katherine C. Chen, Samuel M. Allen, James D. Livingston

Materials Engineering

Systematic studies of alloys based on TiCr, have been performed in order to improve the toughness of Laves phase intermetallics. The extent to which alloy compositions and annealing treatments influence the toughness was quantified by Vickers indentation. The single-phase Laves behavior was first established by studying stoichiometric and nonstoichiometric TiCr,. Next, alloying effects were investigated with ternary Laves phases based on TiCr2. Different microstructures of two-phase alloys consisting of (Ti,Cr)-bcc+TiCr2, were also examined. Various toughening theories based on vacancies, site-substitutions, crystal structure (C14, C36, or Cl5) stabilization, and the presence of a …


Evidence Of Heterogeneous Substructure Development During Primary Creep Of Ti-6al-2sn-4zr-2mo, R. W. Hayes, Cecil Rhodes, Blair London Mar 1995

Evidence Of Heterogeneous Substructure Development During Primary Creep Of Ti-6al-2sn-4zr-2mo, R. W. Hayes, Cecil Rhodes, Blair London

Materials Engineering

No Abstract.


Morphology, Deformation, And Defect Structures Of Ticr2 In Ti-Cr Alloys, Katherine C. Chen, Samuel M. Allen, James D. Livingston Oct 1992

Morphology, Deformation, And Defect Structures Of Ticr2 In Ti-Cr Alloys, Katherine C. Chen, Samuel M. Allen, James D. Livingston

Materials Engineering

The morphologies and defect structures of TiCr2 in several Ti-Cr alloys have been examined by optical metallography, x-ray diffraction, and transmission electron microscopy (TEM), in order to explore the room-temperature deformability of the Laves phase TiCr2. The morphology of the Laves phase was found to be dependent upon alloy composition and annealing temperature. Samples deformed by compression have also been studied using TEM. Comparisons of microstructures before and after deformation suggest an increase in twin, stacking faul4 and dislocation density within the Laves phase, indicating some but not extensive room-temperature deformability.


On The Creep Deformation Of A Cast Near Gamma Tial Alloy Ti-48al-1nb, R. W. Hayes, B. London Sep 1992

On The Creep Deformation Of A Cast Near Gamma Tial Alloy Ti-48al-1nb, R. W. Hayes, B. London

Materials Engineering

The steady-state creep deformation behavior of a cast two phase gamma TiAl alloy having the composition Ti---48Al---1Nb (at.%) has been studied. Tension creep tests using the stress increment technique (θθ2θ3) were conducted over the temperature range of 704–850°C at constant initial applied stress level of 103.4–241.3 MPa. The activation energy for creep over the temperature and stress regime of this study varied 317.5 kJ/mol (137.8 MPa) up to 341.0 kJ/mol (206.8 MPa) with an average value of 326.4 kJ/mol. This is well within the range of values previously measured for gamma TiAl alloys where creep controlled by volume diffusion has …


Steady-State Creep Deformation Of Investment Cast Near-Gamma Titanium Aluminide, D. A. Wheeler, B. London, D. E. Larsen Jr. Mar 1992

Steady-State Creep Deformation Of Investment Cast Near-Gamma Titanium Aluminide, D. A. Wheeler, B. London, D. E. Larsen Jr.

Materials Engineering

No Abstract.


Application Of Optical Emission Diagnostics And Control Related To Semiconductor Processing, Richard N. Savage, Greg C. Viloria Jan 1992

Application Of Optical Emission Diagnostics And Control Related To Semiconductor Processing, Richard N. Savage, Greg C. Viloria

Materials Engineering

This paper discusses and shows applications of optical emission spectroscopy techniques and methods to monitor plasma emissions during semiconductor processing. A brief discussion of the instrumentation that was used and the software to control the instrumentation is presented. Optical emission spectroscopy techniques discussed include chemical species identification in plasma etching, process fingerprinting, contamination detection, endpoint analysis/control, and sputter/deposition plasma monitoring.


Apparatus And Method For Automatically Identifying Chemical Species Within A Plasma Reactor Environment, Richard N. Savage May 1991

Apparatus And Method For Automatically Identifying Chemical Species Within A Plasma Reactor Environment, Richard N. Savage

Materials Engineering

A method and apparatus to control the plasma environment in a semiconductor or thin-film fabrication chamber. The apparatus and method include a means for measuring an optical emission spectrum of the chemical species in the plasma and a library containing a multiplicity of predefined spectral patterns. A processor automatically correlates the spectrum with the predefined spectral patterns in the library, and yields a correlation value for all the correlations. A subset of the predefined spectral patterns based upon the highest correlation values are selected and used to identify the chemical species and abundances thereof in the plasma. A comparator compares …


In-Situ Film Thickness Measurements For Real-Time Monitoring And Control Of Advanced Photoresist Track Coating Systems, Richard N. Savage, Thomas E. Metz, Horace O. Simmons Jan 1991

In-Situ Film Thickness Measurements For Real-Time Monitoring And Control Of Advanced Photoresist Track Coating Systems, Richard N. Savage, Thomas E. Metz, Horace O. Simmons

Materials Engineering

This paper explores the methodologies of real-time measurement of photoresist film thickness on silicon wafers using multi-wavelength reflection interferometry. Reflected light from the wafer's surface, containing the interference profile, is collected in-situ via a fiber optic cable and film thickness is determined in real-time via a pattern recognition algorithm. The instrumentation used to make this measurement and its application toward optimizing track performance during spin-coating and back are discussed. Data demonstrating basic thickness versus spin-time and thickness versus bake-time profiles acquired on-line without process disruption are presented along with its utilization toward minimizing process set-up and machine qualification. Moreover, the …


In-Line Photoresist Thickness Monitor, Richard N. Savage, Tom W. Batchelder, Kenneth M. Sautter, Gary H. Memovich Dec 1990

In-Line Photoresist Thickness Monitor, Richard N. Savage, Tom W. Batchelder, Kenneth M. Sautter, Gary H. Memovich

Materials Engineering

An in-line photoresist thickness measuring device wherein a plurality of projection optical fibers are disposed over a wafer processing track for illuminating portions of a wafer as the wafer proceeds along the track. The light scattered back from each illuminated portion is detected by a corresponding plurality of pickup optical fibers and communicated to an optical fiber multiplexer. The multiplexer sequentially selects the optical signal from each pickup optical fiber and communicates the light from the selected pickup optical fiber to a spectrometer. The spectrometer simultaneously diffuses the scattered light into a plurality of light bands, each light band having …


Real-Time, In-Situ Measurement Of Film Thickness And Uniformity During Plasma Ashing Of Photoresist, Richard N. Savage, Horace Simmons, John T. Davies, Thomas Metz Aug 1990

Real-Time, In-Situ Measurement Of Film Thickness And Uniformity During Plasma Ashing Of Photoresist, Richard N. Savage, Horace Simmons, John T. Davies, Thomas Metz

Materials Engineering

This paper will discuss the performance of equipment which monitors and so controls photoresist thickness and uniformity during plasma ashing without interfering with the process. Practical monitoring of a subtractive process of this type is significantly more complex than monitoring deposition processes. An initial absolute thickness measurement is needed. In addition the device must view the layer through a luminous medium and cannot rely on simple optical interference fringe counting. The equipment is self-calibrating and sensitive to layers dnm thick. An application to partial plasma resist ashing in high uniformity equipment will be described. Application to other films (e. g. …


Optical Switch, Richard N. Savage Jul 1990

Optical Switch, Richard N. Savage

Materials Engineering

An optical switch for transmitting light between a first location and a selected one of a plurality of second locations. The switch includes a mirror having a concave, reflective surface and an axis. The switch also includes a plurality of fiber optic cables, one of which is disposed at the first location and the remainder of which are disposed at the second locations, each cable having a light transmission face at their respective locations. The light transmission face at the first location is substantially parallel to the focal plane of the mirror. The light transmission face at each of the …


Using Living Materials To Intervene In The Natural Succession Process To Accelerate The Re-Development Of A Self-Sustaining Ecosystem That Has Been Damaged By Human Intervention, Eric Jorgensen Jan 1989

Using Living Materials To Intervene In The Natural Succession Process To Accelerate The Re-Development Of A Self-Sustaining Ecosystem That Has Been Damaged By Human Intervention, Eric Jorgensen

Materials Engineering

No abstract provided.


New Specimen Design For Studying The Growth Of Small Fatigue Cracks With Surface Acoustic Waves, Blair London Aug 1985

New Specimen Design For Studying The Growth Of Small Fatigue Cracks With Surface Acoustic Waves, Blair London

Materials Engineering

The study of small surface fatigue cracks in AISI 4140 quenched and tempered steel by a nondestructive surface acoustic wave technique is summarized. A novel cantilevered bending, plate-type fatigue specimen is described that is compatible with the acoustic method. Small cracks are initiated from a 25-μm deep surface pit produced by an electrospark machine. The importance of studying these


Applications Of Optical Emission Spectroscopy To Semiconductor Processing, Richard N. Savage, John G. Shabushnig, Paul R. Demko Jan 1985

Applications Of Optical Emission Spectroscopy To Semiconductor Processing, Richard N. Savage, John G. Shabushnig, Paul R. Demko

Materials Engineering

Optical emission spectroscopy (OES) has proven to be a valuable tool in the developmrent and production of state-of-the-art semiconductor devices. Application to the plasma etching of a variety of materials necessary for integrated circuit fabrication is discussed, with particular emphasis placed on etch endpoint analysis. The utility of OES techniques in monitoring photolithographic processes is also presented.


Speciation Of Cr (Iii) And Cr (Vi) Via Reversed Phase Hplc With Inductively Coupled Plasma Emission Spectroscopic Detection (Hplc-Icp)24, Richard N. Savage, I. S. Krull, D. Bushee, R. G. Schleicher, S. B. Smith, Jr. Dec 1982

Speciation Of Cr (Iii) And Cr (Vi) Via Reversed Phase Hplc With Inductively Coupled Plasma Emission Spectroscopic Detection (Hplc-Icp)24, Richard N. Savage, I. S. Krull, D. Bushee, R. G. Schleicher, S. B. Smith, Jr.

Materials Engineering

Chromium ions, viz., chromic (Cr+3 = III) and chromate (Cr+6 = VI), can be reliably, conveniently, reproducibly, and quickly separated and detected by the use of conventional paired-ion, reversed phase (RP) high performance liquid chromatography (HPLC) together with refractive index (RI) and/or inductively coupled plasma emission spectroscopic (ICP) detection. A number of novel paired-ion approaches have now been developed, using PIC A (tetrabutylammonium hydroxide) or PIC B (sodium n-alkyl sulfonate) separately in the mobile phase. This allows for the retention of each Cr species depending on the particular ion pairing reagent being used, while the remaining Cr ion …


Metal Cation/Anion Speciation Via Paired-Ion, Reversed Phase Hplc With Refractive Index And/Or Inductively Coupled Plasma Emission Spectroscopic Detection Methods, Richard N. Savage, D. Bushee, I. S. Krull, S. B. Smith, Jr. Jan 1982

Metal Cation/Anion Speciation Via Paired-Ion, Reversed Phase Hplc With Refractive Index And/Or Inductively Coupled Plasma Emission Spectroscopic Detection Methods, Richard N. Savage, D. Bushee, I. S. Krull, S. B. Smith, Jr.

Materials Engineering

Conventional high performance liquid chromatography instrumentation and packing materials can be inexpensively and rapidly utilized for the qualitative and quantitative analysis of various metal cations or anions. The final approaches utilize reversed phase HPLC in the form of paired-ion separations. The detection of individually eluted, fully resolved metal cations or anions is possible via conventional refractive index or inductively coupled plasma emission spectroscopic detection. In many cases, unresolved mixtures of metal cations, eluted as a single peak on HPLC, can be resolved and identified via the use of ICP detection. Both metal cations and anions can be easily resolved, according …


Development And Characterization Of A 9-Mm Inductively-Coupled Argon Plasma Source For Atomic Emission Spectrometry, A. D. Weiss, Richard N. Savage, G. M. Hieftje Mar 1981

Development And Characterization Of A 9-Mm Inductively-Coupled Argon Plasma Source For Atomic Emission Spectrometry, A. D. Weiss, Richard N. Savage, G. M. Hieftje

Materials Engineering

A new 9-mm (i.d.) inductively-coupled plasma (ICP) torch is described which supports a stable, analytically useful plasma at less than 500 W of r.f. power and 7 l min-1 total argon gas flow. Detection limits, working curves and other analytical characteristics of the new device are compared with those of both a miniature (13-mm i.d.) and conventional (19-mm i.d.) ICP. Although temperatures of the new plasma are somewhat lower than those in the larger plasmas, the new system offers promise for future, miniaturized ICP instruments.


Characteristics Of The Background Emission Spectrum From A Miniature Inductively-Coupled Plasma, Richard N. Savage, G. M. Hieftje Jan 1981

Characteristics Of The Background Emission Spectrum From A Miniature Inductively-Coupled Plasma, Richard N. Savage, G. M. Hieftje

Materials Engineering

The spectral characteristics of the background radiation emitted by a miniature inductively-coupled plasma (i.c.p.) are carefully examined and methods for reducing undesirable features discussed. The complex nature of the background emission spectrum for the mini-i.c.p. indicates that careful line selection criteria and background correction procedures should be employed. Extending the torch coolant tube to the bottom of the region being observed in the plasma proved to be the most effective method for reducing undesirable spectral band features. Acute changes in background emission levels with r.f. power and nebulizer gas flow rates emphasize the need for careful control of these parameters …


Enhancement Of Pneumatic Nebulization Efficiency Through Application Of An Electric Field, Richard N. Savage, G. M. Hieftje Oct 1978

Enhancement Of Pneumatic Nebulization Efficiency Through Application Of An Electric Field, Richard N. Savage, G. M. Hieftje

Materials Engineering

A novel technique is described for reducing the size of aerosol droplets produced by a pneumatic nebulizer of the kind commonly used in flame or plasma spectrometry. The technique involves the application of an electric field to the tip of the nebulizer, resulting in an induced surface charge on the liquid being nebulized. In turn, the surface charge reduces the liquid's surface tension and results in the generation of a finer aerosol. In this study, the effect of the electric field is quantified in terms of the spatial dispersion and size distribution of aerosol droplets formed in the presence and …