Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Mechanical Engineering (29)
- Manufacturing (24)
- Structural Materials (18)
- Applied Mechanics (13)
- Engineering Mechanics (13)
-
- Engineering Science and Materials (13)
- Mechanics of Materials (13)
- Civil and Environmental Engineering (12)
- Physical Sciences and Mathematics (8)
- Aerospace Engineering (5)
- Ceramic Materials (5)
- Physics (5)
- Chemistry (3)
- Electrical and Computer Engineering (3)
- Biochemical and Biomolecular Engineering (1)
- Chemical Engineering (1)
- Mining Engineering (1)
- Structural Engineering (1)
- Keyword
-
- Friction stir processing (18)
- Microstructure (8)
- Additive Manufacturing (6)
- Mechanical properties (5)
- Superplasticity (5)
-
- Additive manufacturing (4)
- Aluminum alloys (4)
- Fatigue (4)
- Friction stir welding (4)
- Grain refinement (4)
- Magnesium alloy (4)
- Additives (3)
- Al alloys (3)
- Cast iron (3)
- Inclusion analysis (3)
- Laser powder bed fusion (3)
- Magnesium alloys (3)
- Solidification (3)
- Steel (3)
- 17-4 PH (2)
- Air entrapment (2)
- Casting (2)
- Copper Powder (2)
- Creep (2)
- Directed Energy Deposition (2)
- Distributed Sensing (2)
- Ductile iron (2)
- Ductility (2)
- EBSD (2)
- Electron Beam Powder Bed Fusion (2)
Articles 151 - 180 of 249
Full-Text Articles in Metallurgy
Vacancy Clustering In Quenched Al-Li Solid Solution Alloys Studied By Doppler Broadening Spectroscopy, Hollis P. Leighly, P. G. Coleman
Vacancy Clustering In Quenched Al-Li Solid Solution Alloys Studied By Doppler Broadening Spectroscopy, Hollis P. Leighly, P. G. Coleman
Materials Science and Engineering Faculty Research & Creative Works
The clustering of vacancies in severely quenched Al-Li solid solution alloys, with Li content between 230 and 2760 ppm, has been studied using Doppler broadening spectroscopy. The alloy samples were initially annealed at 873 K in dry air or dry, pure nitrogen. The onset temperature for vacancy clustering in samples initially annealed in air was found to be 150 ± 10 K, 40 ± 15 K lower than for the nitrogen-annealed samples. This result is consistent with the migration of divacancies, formed as a result of the significant increase in vacancy concentration caused by Li migration to, and oxidation at, …
Electrodeposition Of Copper On Thermally Oxidized 316 L Stainless Steel Substrates, Z. Zhou, Thomas J. O'Keefe
Electrodeposition Of Copper On Thermally Oxidized 316 L Stainless Steel Substrates, Z. Zhou, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
The effect of thermal oxidation of 316 L stainless steel cathode blanks used in copper electrodeposition was studied. Current and potential step experiments were performed to evaluate electrochemical changes caused by the oxidation treatments. SEM and AES were used to characterize the stainless-steel substrates and the deposited copper films. Particular emphasis was given to the initial stages of copper nucleation and growth. The copper electro crystallization process was strongly influenced by the temperature employed in oxidizing the stainless steel. Dense, uniform and fine copper nuclei were obtained on the stainless-steel substrate oxidized in air at 200°C and 300°C for 3 …
Analysis Of The Value Of The Fe Examination For The Assessment Of Student Learning In Engineering And Science Topics, John L. Watson
Analysis Of The Value Of The Fe Examination For The Assessment Of Student Learning In Engineering And Science Topics, John L. Watson
Materials Science and Engineering Faculty Research & Creative Works
This paper presents the results of a project, which investigated the potential of fully using previously unreleased data from the nationally normed Fundamentals of Engineering (FE) examination to assess learning in key engineering and science topics. In the past, very limited information was released by the National Council of Examiners for Engineers and Surveyors (NCEES) for the eight hour FE examination, which is composed of 150-200 questions in ten morning and five afternoon topics. For the purposes of this project the NCEES agreed to release information to the University of Missouri-Rolla (UMR) to permit the value of the FE data …
Organically Deposited Metallic Films For Device Fabrication, Thomas J. O'Keefe, M. Stroder, Matthew O'Keefe
Organically Deposited Metallic Films For Device Fabrication, Thomas J. O'Keefe, M. Stroder, Matthew O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
Advances in integrated circuit density, speed and complexity are dependent on lower resistance, finer line width on-chip interconnections. Methods for incorporating copper interconnects into IC fabrication processes have been developed which accomplish this objective but most of these methods use some form of blanket metal deposition that requires mechanical and/or chemical removal of excess material. To date, investigations into the selective deposition of conductor materials for device fabrication have met with limited success. A new process for selectively depositing metallic conductors using inexpensive, organic-based chemical solutions could potentially force a paradigm shift in the deposition of metals for microelectronic applications. …
Maskless, Direct Deposition Of Copper Onto Aluminum Bond Pads For Flip Chip Applications, M. Fang, Thomas J. O'Keefe, M. Stroder, W. Shih, Matthew O'Keefe, R. Strawser, D. Via
Maskless, Direct Deposition Of Copper Onto Aluminum Bond Pads For Flip Chip Applications, M. Fang, Thomas J. O'Keefe, M. Stroder, W. Shih, Matthew O'Keefe, R. Strawser, D. Via
Materials Science and Engineering Faculty Research & Creative Works
Flip chip interconnection of integrated circuits (IC) for packaging applications such as direct chip attachment use Pb-Sn solders as the connection between the die and the substrate. Under bump metallization is typically used to transition from the non-solderable Al bond pad on the IC to a solderable surface such as copper using traditional blanket metal deposition, photolithography and etching procedures. In this study, we report for the first time the use of a novel process for selectively depositing adherent copper directly onto aluminum thin films, eliminating the need for adhesion promoting transition layers and additional patterning steps. Utilizing copper bearing …
Strip Casting With Fluxing Agent Applied To Casting Roll, Robert S. Williams, Ronald J. O'Malley, Richard C. Sussman
Strip Casting With Fluxing Agent Applied To Casting Roll, Robert S. Williams, Ronald J. O'Malley, Richard C. Sussman
Materials Science and Engineering Faculty Research & Creative Works
A strip caster (10) for producing a continuous strip (24) includes a tundish (12) for containing a melt (14), a pair of horizontally disposed water cooled casting rolls (22) and devices (29) for electrostatically coating the outer peripheral chill surfaces (44) of the casting rolls with a powder flux material (56). The casting rolls are juxtaposed relative to one another for forming a pouting basin (18) for receiving the melt through a teeming tube (16) thereby establishing a meniscus (20) between the rolls for forming the strip. The melt is protected from the outside air by a non-oxidizing gas passed …
The Effect Of Casting Shape And Size On Solidification Time: A New Approach, Murat Tiryakioǧlu, Ergin Tiryakioǧlu, Donald R. Askeland
The Effect Of Casting Shape And Size On Solidification Time: A New Approach, Murat Tiryakioǧlu, Ergin Tiryakioǧlu, Donald R. Askeland
Materials Science and Engineering Faculty Research & Creative Works
The limitations of Chvorinov's Rule for predicting the solidification time of a casting are discussed and previous studies intended to modify Chvorinov's Rule in order to express the effect of the size and shape of castings on solidification time are reviewed. A new model that introduces a shape factor is presented that predicts the solidification times of castings as well as or better than Chvorinov's Rule, particularly for more complex shapes. The validity of the new model is compared with the conventional Chvorinov's Rule by a statistical analysis of twelve sets of data obtained from the literature.
A Positron Annihilation Study Of Rotating Beam Fatigue Damage In The Superalloy Haynes 188, D. Hoeckelman, Hollis P. Leighly
A Positron Annihilation Study Of Rotating Beam Fatigue Damage In The Superalloy Haynes 188, D. Hoeckelman, Hollis P. Leighly
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.
Effect Of Additives On Anomalous Deposition In Zinc-Cobalt Alloy Electrogalvanizing, H. M. Wang, Thomas J. O'Keefe
Effect Of Additives On Anomalous Deposition In Zinc-Cobalt Alloy Electrogalvanizing, H. M. Wang, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
Alloys of Zn-Co were deposited from sulphate electrolytes containing various additives to study their influence on the anomalous behavior of the reactions. The effects of antimony, germanium and arsenic on the Zn-Co alloy composition and structure were examined. The results showed that the composition and structure of Zn-Co alloys deposited could be dramatically changed by antimony, and to a lesser extent by germanium and arsenic. A concentration of Sb(III) as low as 5 mg dm-3 increased the cobalt content by a factor of approximately 3; however, the deposit morphology was very dendritic. Germanium additions nearly doubled the cobalt content and …
Characterization Of Phase Transformation Behavior In Electrolytically Produced Indium-Thallium Shape Memory Alloy Films, Chong Ho Sonu, Thomas J. O'Keefe
Characterization Of Phase Transformation Behavior In Electrolytically Produced Indium-Thallium Shape Memory Alloy Films, Chong Ho Sonu, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
Indium-thallium alloys in the range 15-38 at. % Tl were electrodeposited from a sulfate electrolyte by using pulsed current. The relationship between composition and phase structure of the alloys deposited was investigated with regard to the shape memory effect. To date there have been no reported experimental studies describing the electrodeposition of InTl alloys capable of undergoing such transformations. Not only did the deposited alloys exhibit the shape memory effect, but the composition-phase relationship exhibited was shown to deviate from that reported for alloys in an equilibrium condition. The results show that the temperature and the temperature interval for the …
Positron Annihilation Determination Of Damage Caused By Fatigue Cycling In The Superalloy Haynes 188, D. Hoeckelman, Hollis P. Leighly
Positron Annihilation Determination Of Damage Caused By Fatigue Cycling In The Superalloy Haynes 188, D. Hoeckelman, Hollis P. Leighly
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.
Density Changes During Isothermal Annealing Of A Quenched Pb–7.45 At% Sn Alloy, Hollis P. Leighly, A. Belaidi
Density Changes During Isothermal Annealing Of A Quenched Pb–7.45 At% Sn Alloy, Hollis P. Leighly, A. Belaidi
Materials Science and Engineering Faculty Research & Creative Works
The increase in density of a Pb–7.45 at% Sn alloy annealed at 150, 165, 180, and 195 °C and quenched at 20, 21.5, 23, 25, and 30 °C is measured isothermally. This increase in density accompanies the formation of the Sn‐rich phase precipitating as a function of time at the quenching temperature. The quenching is rapid enough to retain some vacancies at equilibrium at the annealing temperature. These vacancies accelerate the early stages of precipitation. The change in density versus time obeys the kinetic law allowing the determination of the reaction rate constant for several annealing and quenching conditions. Copyright …
The Influence Of Matrix Microstructure, G. M. Vyletel, J. E. Allison, David C. Van Aken
The Influence Of Matrix Microstructure, G. M. Vyletel, J. E. Allison, David C. Van Aken
Materials Science and Engineering Faculty Research & Creative Works
The low-cycle and high-cycle fatigue behavior and cyclic response of naturally aged and artificially aged 2219/TiC/15p and unreinforced 2219 Al were investigated utilizing plastic strain-controlled and stress-controlled testing. The cyclic response of both the reinforced and un-reinforced materials was similar for all plastic strain amplitudes tested except that the saturation stress level for the composite was always greater than that of the unreinforced material. The cyclic response of the naturally aged materials exhibited cyclic hardening and, in some cases, cyclic softening, while the cyclic response for the artificially aged materials showed no evidence of either cyclic hardening or softening. The …
A Study Of Fatigue Failure In Superalloys Using Positron Annihilation, D. Hoeckelman, Hollis P. Leighly
A Study Of Fatigue Failure In Superalloys Using Positron Annihilation, D. Hoeckelman, Hollis P. Leighly
Materials Science and Engineering Faculty Research & Creative Works
This study shows there are significant changes occurring in the open volume defect concentration during fatigue cycling as measured by the S parameter. These changes are dependent upon the stress ratio, R = σmin/σmax, the maximum stress, σmax, and the number of fatigue cycles. The decline in the S parameter is due to the elimination of the residual vacancies. This decline is followed by an increase due to the generation of dislocations and the formation of small microcracks. This is followed by a decline in the S parameter due to growth of the microcracks ultimately leading to failure. Copyright © …
Electrochemical Evaluation Of The Adherence Of Zinc To Aluminum Cathodes, Jang Sop Han, Thomas J. O'Keefe
Electrochemical Evaluation Of The Adherence Of Zinc To Aluminum Cathodes, Jang Sop Han, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
Excess fluoride ions in zinc electrolyte are known to cause problems with the removal of electrowon zinc from aluminum blanks. The mechanisms responsible for this undesirable adherence were studied. Acid zinc sulfate electrolyte similar to that employed in zinc electrowinning was used. Using electrolyte containing various fluoride ion concentrations, the initial nucleation and growth morphology of zinc and the aluminum electrode surface were examined using scanning electron microscopy. Electrochemical tests were also carried out in various solutions to obtain a better understanding of the polarization behavior of the system. © 1992.
The Effect Of Additives On The Nucleation And Growth Of Copper Onto Stainless Steel Cathodes, M. Sun, Thomas J. O'Keefe
The Effect Of Additives On The Nucleation And Growth Of Copper Onto Stainless Steel Cathodes, M. Sun, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
A potentiostatic technique has been used to study the effects of chloride ion, glue, and thiourea on the initial electrodeposition of copper. A stainless steel (AISI 304) rotating disc electrode (RDE) with an electrolyte containing 40 g/1 Cu2+ and 180 g/1 H2SO4 at 40 °C was employed. The current transients from the potential step measurements for the additive-free electrolyte could be fitted to a model that assumed progressive nucleation followed by growth of three-dimensional (3-D) centers under diffusion control. The growth mechanism and the type of nuclei were also confirmed by scanning electron microscopy (SEM) of …
The Degradation Of Aluminium Cathodes By Fluoride Ion During Zinc Electrowinning, J. S. Han, Thomas J. O'Keefe
The Degradation Of Aluminium Cathodes By Fluoride Ion During Zinc Electrowinning, J. S. Han, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
The influence of fluoride ions on aluminum cathode surface degradation during zinc electrowinning has been studied. Electrolyte with a composition similar to that employed in plant operations has been used. A direct correlation is shown between the electrolyte fluoride content and the number of deposition cycles possible before zinc removal becomes difficult. The role of initial nucleation and starting electrode morphology is discussed in terms of the degree of adherence observed. Electrochemical tests have also been made on the electrodes at various stages of the process in an attempt to gain a better fundamental understanding of the mechanisms responsible for …
Effect Of Ultrasound On Acidified Brine Leaching Of Double-Kiln Treated Eaf Dust, J. A. Barrera-Godinez, Thomas J. O'Keefe, Johh L. Watson
Effect Of Ultrasound On Acidified Brine Leaching Of Double-Kiln Treated Eaf Dust, J. A. Barrera-Godinez, Thomas J. O'Keefe, Johh L. Watson
Materials Science and Engineering Faculty Research & Creative Works
The U.S. steel industry produces approximately 500,000 tons/year of electric arc furnace (EAF) dust, which is classified as a hazardous waste. Increasing disposal costs of these dusts have encouraged studies to investigate treatment processes to render the material non-hazardous, and to possibly recover metal values. This research project was designed to examine the hydrometallurgical recovery of zinc from EAF dusts that have been treated by a double kiln fuming process. The test work consisted essentially of acidified brine leaching of the pelletized calcine to determine the influence of traditional conditions, such as acid concentration, temperature and agitation, plus the application …
Sme Annual Meeting. Phoenix, Usa. February 22-27, 1992, Johh L. Watson
Sme Annual Meeting. Phoenix, Usa. February 22-27, 1992, Johh L. Watson
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.
Solvent Extraction Reagent Entrainment Effects On Zinc Electrowinning From Waste Oxide Leach Solutions, M. Neira, Thomas J. O'Keefe, Johh L. Watson
Solvent Extraction Reagent Entrainment Effects On Zinc Electrowinning From Waste Oxide Leach Solutions, M. Neira, Thomas J. O'Keefe, Johh L. Watson
Materials Science and Engineering Faculty Research & Creative Works
A considerable quantity of metal-containing waste oxide is generated by the primary metal industry, and under increased environmental regulation, treatment of these wastes has become viable. Hydrometallurgical processing is often appropriate and one potential treatment process for zinc oxide wastes involves leaching the oxide with an acid, purifying by a solvent extraction operation, and recovering metallic zinc by electrowinning the purified leach solution. The purification stage is frequently critical and the introduction of a solvent extraction organic reagent into the flowsheet can be detrimental to downstream processes. The object of this study was to determine the effect of organics, entrained …
Positron Study Of Defects And Diffusion Induced Grain Boundary Migration In A Pb-Sn System, A. Belaidi, Hollis P. Leighly, H. Aourag, B. Khelifa, M. Oubadi, A. Elias
Positron Study Of Defects And Diffusion Induced Grain Boundary Migration In A Pb-Sn System, A. Belaidi, Hollis P. Leighly, H. Aourag, B. Khelifa, M. Oubadi, A. Elias
Materials Science and Engineering Faculty Research & Creative Works
The Pb-Sn system discloses a remarkable effect at the intermediate α → α + β phase boundary. The observation of the sharp transient peak in the S-parameter curve which is analogous to those found in thermal capacity curves is, as far as the authors are aware, unique in such positron measurements. This effect is interpreted in terms of positron trapping in defects associated with the strains accompanying the initial stage of transformation. This short note offers a new approach to the underlying phenomenon published in J. Phys. F. Met. Phys., 12 (1982) 813 by A. Belaidi, H. P. Leighly Jr. …
Electrochemical Evaluation Of Copper Deposition With Gas Sparging, D. A. Uceda, Thomas J. O'Keefe
Electrochemical Evaluation Of Copper Deposition With Gas Sparging, D. A. Uceda, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
The influence of gas sparging during copper electrolysis was studied using standard electrochemical techniques. The polarization behavior of acid copper electrolytes was determined in the presence and absence of gas sparging on vertical electrodes. Tracer ion techniques were employed to determine the effect of gas sparging and forced circulation of the electrolyte on the mass transfer characteristics of the system. In addition to the potentiodynamic scans, 3-h copper deposits were produced for morphology and orientation studies. The effect of current density and temperature on deposition were also studied. The polarization experiments have shown that a mass transfer component becomes evident …
The Effects Of Lead On The Electrochemical And Adhesion Behavior Of Zinc Electrodeposits, Vijay Srinivasan, J. Sami Cuzmar, Thomas J. O'Keefe
The Effects Of Lead On The Electrochemical And Adhesion Behavior Of Zinc Electrodeposits, Vijay Srinivasan, J. Sami Cuzmar, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
The presence of excessive lead in zinc sulfate electrolytes can lead to problems related to both processing efficiency and the properties of the metal produced. For example, poor adhesion can occur in electrogalvanized steel when it is heated in the temperature range of 215 °C to 280 °C if lead is present in the deposit. The duration of heating necessary to induce the peeling of the zinc was found to be dependent on the temperature, time, and concentration of lead in the electrolyte and the plating parameters. The presence of lead slowed the formation of the intermetallic, and the peeling …
Comments On The Papers By Kê And Su, Hollis P. Leighly
Comments On The Papers By Kê And Su, Hollis P. Leighly
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.
Production Of Thin Copper Foils On Microporous Titanium Oxide Substrates, J. L. Delplancke, M. Sun, Thomas J. O'Keefe, R. Winand
Production Of Thin Copper Foils On Microporous Titanium Oxide Substrates, J. L. Delplancke, M. Sun, Thomas J. O'Keefe, R. Winand
Materials Science and Engineering Faculty Research & Creative Works
This study deals with the electrochemical production of thin (35 μm) copper films on anodized titanium substrates. The formation of a microporous oxide layer on the titanium electrodes greatly enhances the surface density of copper nuclei during a potentiostatic experiment so that a complete coverage of the cathode surfaces may be obtained after short term (20 s) polarization. Moreover, the oxide film may act as a parting agent and the copper films may be easily stripped from their substrates. The higher the pore density of the oxide film, the higher the surface density of nuclei and the easier the foil's …
Mass-Transfer Measurements Of Copper Deposition In A Fluosilicate Electrolyte, D. Uceda, Thomas J. O'Keefe, E. Cole
Mass-Transfer Measurements Of Copper Deposition In A Fluosilicate Electrolyte, D. Uceda, Thomas J. O'Keefe, E. Cole
Materials Science and Engineering Faculty Research & Creative Works
The electrodeposition of copper from a fluosilicate electrolyte has been investigated by electrochemical techniques, x-ray diffraction, and scanning electron microscopy. The diffusion coefficient of cupric ion in a fluosilicate solution has been determined with the aid of a rotating disk electrode using the mixed control Levich equation. Gold (Au+3) was used as a tracer to evaluate the mass transport properties of the system. The polarization behavior of the electrolyte was measured in the presence and absence of gas sparging on a vertical stationary electrode to study the effect of the mass transport contribution. Sound copper deposits were obtained …
Evaluation Of Mass Transport In Copper And Zinc Electrodeposition Using Tracer Methods, H. M. Wang, S. F. Chen, Thomas J. O'Keefe, M. Degrez, R. Winand
Evaluation Of Mass Transport In Copper And Zinc Electrodeposition Using Tracer Methods, H. M. Wang, S. F. Chen, Thomas J. O'Keefe, M. Degrez, R. Winand
Materials Science and Engineering Faculty Research & Creative Works
Control of the electro crystallization process is essential in the deposition of metals from aqueous electrolytes. A knowledge of the influence of mass transfer on the metal ion reduction is a critical element in any number of electrolytic processes, particularly where relatively high current densities are desired. The use of more positive ion tracer techniques as a means of experimentally determining some of the mass transport properties of interest are described. Examples for copper, zinc and zinc alloys electrolysis are included. © 1989 Chapman and Hall Ltd.
Nucleation Of Electrodeposited Copper On Anodized Titanium, J. L. Delplancke, M. Sun, Thomas J. O'Keefe, R. Winand
Nucleation Of Electrodeposited Copper On Anodized Titanium, J. L. Delplancke, M. Sun, Thomas J. O'Keefe, R. Winand
Materials Science and Engineering Faculty Research & Creative Works
A study has been made to determine the effect of an electrochemically produced titanium-oxide film on the nucleation of copper. The oxide films were made galvanostatically at 25°C in 1 M sulphuric acid on pure titanium metal. Potentiodynamic, potential step and current step experiments were performed in an additive-free copper sulphate-sulphuric acid electrolyte at 25°C. It was found that the oxide film played an important role during nucleation. By increasing the thickness of the anodic film, it was possible to decrease the diameter and to increase the surface density of copper nuclei. The kinetics of nucleation and growth of the …
Premartensitic Anelasticity In Indium-Thallium Alloys., Manfred Wuttig, C. Y. Lei, Tetsuro Suzuki
Premartensitic Anelasticity In Indium-Thallium Alloys., Manfred Wuttig, C. Y. Lei, Tetsuro Suzuki
Materials Science and Engineering Faculty Research & Creative Works
The linear and nonlinear low frequency internal friction of In-24 at. pct Tl displays a Curie-Weiss type behavior in the temperature range above the transformation temperature. The critical temperature equals the martensite start temperature. It is proposed that the origin of the observed internal friction is the diffusion-controlled interaction of substitutional atoms with the premartensitic strain modulation, tweed.
Comments On A Paper By No, Esnouf, San Juan, And Fontozzi, Hollis P. Leighly
Comments On A Paper By No, Esnouf, San Juan, And Fontozzi, Hollis P. Leighly
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.