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Effect Of Microstructural Features On Steel Machinability, Mark C. Emmendorfer 2018 Missouri University of Science and Technology

Effect Of Microstructural Features On Steel Machinability, Mark C. Emmendorfer

Masters Theses

Non-metallic inclusions can have a tremendous impact on the machinability of steel. Some oxide inclusions such as alumina, spinel, and other refractory abrasive oxide inclusions can have a detrimental effect on machinability. Modification of oxide inclusions by calcium treatment can promote the formation of low melting point oxides such as anorthite and gehlenite inclusions that can assist in chip formation and form a lubricating layer on the rake surface of the machine tool. MnS is known to be beneficial to improving the machinability of steel. They assist in chip formation by being heavily deformed in the primary shear zone. Sulfide ...


Phase Transitions And Their Interaction With Dislocations In Silicon, Valery I. Levitas, Hao Chen, Liming Xiong 2018 Iowa State University

Phase Transitions And Their Interaction With Dislocations In Silicon, Valery I. Levitas, Hao Chen, Liming Xiong

Aerospace Engineering Publications

In this paper, phase transformations (PTs) in silicon were investigated through molecular dynamics (MD) using Tersoff potential. In the first step, simulations of PTs in single crystal silicon under various stress-controlled loading were carried out. Results shows that all instability points under various stress states are described by criteria, which are linear in the space of normal stresses. There is a region in the stress space in which conditions for direct and reverse PTs coincide and a unique homogeneous phase transition (without nucleation) can be realized. Finally, phase transition in bi-crystalline silicon with a dislocation pileup along the grain boundary ...


Design Of Shape-Conforming Nosecone For Optimal Fluid Flow From Transonic To Supersonic Range, Anna Tombazzi 2018 The University of Akron

Design Of Shape-Conforming Nosecone For Optimal Fluid Flow From Transonic To Supersonic Range, Anna Tombazzi

Williams Honors College, Honors Research Projects

Modern flight vehicles, such as rockets, missiles, and airplanes, experience a force caused by forebody wave drag during the flight. This drag force is induced when the frontal point of each vehicle breaks the pressure wave during flight. Efforts to reduce this wave drag force to improve flight efficiency include modifying the nosecone profile of the flight vehicles to lower the drag force.

This project revolved around creating a design to make the transformation of nosecone shapes from a ¾ Parabolic profile to a ½ Power Series profile possible, mid-flight. Using a novel nosecone assembly, shape memory alloys (SMAs) and ...


Bismuth Ferrite-Based Lead-Free Ceramics And Multilayers With High Recoverable Energy Density, Dawei Wang, Zhongming Fan, Di Zhou, Amir Khesro, Shunsuke Murakami, Antonio Feteira, Quanliang Zhao, Xiaoli Tan, Ian M. Reaney 2018 University of Sheffield

Bismuth Ferrite-Based Lead-Free Ceramics And Multilayers With High Recoverable Energy Density, Dawei Wang, Zhongming Fan, Di Zhou, Amir Khesro, Shunsuke Murakami, Antonio Feteira, Quanliang Zhao, Xiaoli Tan, Ian M. Reaney

Materials Science and Engineering Publications

Lead-free ceramics with high recoverable energy density (Wrec) and energy storage efficiency (η) are attractive for advanced pulsed power capacitors to enable greater miniaturization and integration. In this work, dense bismuth ferrite (BF)-based, lead-free 0.75(Bi1−xNdx)FeO3-0.25BaTiO3 (BNxF-BT) ceramics and multilayers were fabricated. A transition from a mixed pseudocubic and R3c to a purely pseudocubic structure was observed as x increased with the optimum properties obtained for mixed compositions. The highest energy densities, W ∼ 4.1 J cm−3 and Wrec ∼ 1.82 J cm−3, were achieved for BN15F-BT, due to the enhanced breakdown field ...


Interfacial Corrosion Of Copper And The Formation Of Copper Hydroxychloride, Mary Teague, Shengxi Li, Hongbo Cong 2018 The University of Akron

Interfacial Corrosion Of Copper And The Formation Of Copper Hydroxychloride, Mary Teague, Shengxi Li, Hongbo Cong

Williams Honors College, Honors Research Projects

Electrical circuitry is an industry, among many others, heavily using the element of copper. Ensuring the mechanical integrity of Cu is crucial, especially in salt environments, for the multifaceted composition of circuits. 4N NaCl solution (equilibrium concentration in ~84% RH) simulated this three-phase system. Rectangular Cu samples were partially immersed in both ambient and continuous lab air sparging atmospheres to understand waterline corrosion of the metal. Open circuit potentials (OCP) were continuously taken during the immersion testing for a maximum of 5 days. A scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS), Raman spectroscopy, and 3-D ...


Investigation Of 2195 And 2219 Post Weld Heat Treatments For Additive Friction Stir Lap Welds, Matthew Champagne 2017 University of New Orleans

Investigation Of 2195 And 2219 Post Weld Heat Treatments For Additive Friction Stir Lap Welds, Matthew Champagne

University of New Orleans Theses and Dissertations

To evaluate potential uses for friction stir welding in additive manufacturing, two separate parts were fabricated, one of 2195-T84 and the other 2219-T87, utilizing fixed pin techniques and additive lap welds. The parts were cut into samples, artificially aged and subjected to Rockwell hardness (HRB), Vickers hardness, micrographic photography, and metallographic imaging on both pre- and post- heat treatment. Additionally, tensile testing was performed on the heat-treated samples. A comparisons of test results showed a minimal increase in the yield strength of the 2195-T84 samples compared to as-welded tensile results obtained from a previous project. The ultimate tensile strength was ...


On The Edge Of Periodicity: Unconventional Magnetism Of Gd117co56.4sn114.3, J. Liu, Yaroslav Mudryk, D. H. Ryan, Vitalij K. Pecharsky 2017 Iowa State University and Ames Laboratory

On The Edge Of Periodicity: Unconventional Magnetism Of Gd117co56.4sn114.3, J. Liu, Yaroslav Mudryk, D. H. Ryan, Vitalij K. Pecharsky

Ames Laboratory Accepted Manuscripts

Magnetization measurements reveal the onset of magnetic ordering at TC = 65 K followed by three additional magnetic anomalies at T1 = 47 K, T2 = 28 K, and T3 = 11 K in Gd117Co56.4Sn114.3 – a compound with a giant cubic unit cell that crystallizes in the Dy117Co56Sn112 structure type with space group Fm3¯m and lattice parameter a = 30.186 Å. The magnetic ordering temperature increases with applied magnetic field; however, the analysis of magnetic data indicates that antiferromagnetic interactions also play a role in the ground state. AC magnetic susceptibility confirms multiple magnetic anomalies and shows minor frequency dependence. The ...


Material Properties Design Using Simulations And Experiments For Powder Injection Molding Of Lead Zirconate Titanate (Pzt)., Bhushan Pramod Bandiwadekar 2017 University of Louisville

Material Properties Design Using Simulations And Experiments For Powder Injection Molding Of Lead Zirconate Titanate (Pzt)., Bhushan Pramod Bandiwadekar

Electronic Theses and Dissertations

Powder injection molding (PIM) process simulations can be performed to minimize the number of injection molding experiments by estimating material properties necessary for PIM simulations. In current work, lead zirconate titanate (PZT) powder-polymer binder feedstock was compounded for 45 vol. % and 52 vol. % solids loading. PIM experiments on designed micro-pillar array geometry were performed using 52 vol. % PZT. Using PIM experiments results as basis, PIM simulations were performed on designed micro-pillar array geometries to understand the effectiveness of PIM simulations with the use of estimated feedstock properties in predicting molding behavior that have micro-features. Additionally, PIM simulations were performed to ...


Effects Of The Internal Magnetic Field On The Magneto-Mechanical Properties Of Magnetic Shape Memory Alloys, Anthony Hobza 2017 Boise State University

Effects Of The Internal Magnetic Field On The Magneto-Mechanical Properties Of Magnetic Shape Memory Alloys, Anthony Hobza

Boise State University Theses and Dissertations

Shape memory alloys are a class of functional material which recover from large strains without permanent deformation. The strain is accommodated by the displacement of twin boundaries in the martensite phase. The shape memory alloy Ni-Mn-Ga is also ferromagnetic. Ni-Mn-Ga preferentially magnetizes along a certain crystallographic axis. This direction of easy magnetization changes across twin boundaries, such that the directions in neighboring twin domains are nearly perpendicular.

The interaction of magnetic moments and interfaces including the crystal surface and twin boundary interfaces has a large role in the magnetization process of the material. The goal of this study is to ...


Control Of Columnar To Equiaxed Transition In Solidification Macrostructure Of Austenitic Stainless Steel Castings, Semen Naumovich Lekakh, Ronald J. O'Malley, Mark Emmendorfer, Brenton Hrebec 2017 Missouri University of Science and Technology

Control Of Columnar To Equiaxed Transition In Solidification Macrostructure Of Austenitic Stainless Steel Castings, Semen Naumovich Lekakh, Ronald J. O'Malley, Mark Emmendorfer, Brenton Hrebec

Ronald J. O'Malley

Solidification macrostructure is of great importance for the properties and the quality of castings made from austenitic grade stainless steels (ASS) because there are limited options to change as-cast macrostructure in the solid condition. A typical cast macrostructure of ASS has a fine surface chilled zone followed by an elongated dendrite zone, columnar to equiaxed transition (CET) zone, and centrally located equiaxed crystals. Several castings from ASS were produced to determine the effects of casting geometry, chilling, and grain refinement on CET. The transient thermal field in solidified heavy castings was simulated and used to determine an isotherm velocity (V ...


Evolution Of Non-Metallic Inclusions In Foundry Steel Casting Processes, Marc Harris, Von Richards, Ronald J. O'Malley, Semen Naumovich Lekakh 2017 Missouri University of Science and Technology

Evolution Of Non-Metallic Inclusions In Foundry Steel Casting Processes, Marc Harris, Von Richards, Ronald J. O'Malley, Semen Naumovich Lekakh

Ronald J. O'Malley

The evolution of nonmetallic inclusions was examined for 4320 steel at an industrial steel foundry. The steel was followed from electric arc furnace melting through ladle refining to final casting. Timed sampling was performed at all stages of the process. Samples were analyzed using an automated SEM/EDS system. The overall evolution of oxide inclusions in terms of nucleation, growth, and flotation during liquid processing was studied using area fraction and average diameter. Chemical composition evolution was observed using a joint ternary plotting tool developed under this program. It was found that the use of zirconium as an addition for ...


Effect Of Zinc Galvanization On The Microstructure And Fracture Behavior Of Low And Medium Carbon Structural Steels, Ignatius C. Okafor, Ronald J. O'Malley, Kaushal R. Prayakarao, Heshmat A. Aglan 2017 Missouri University of Science and Technology

Effect Of Zinc Galvanization On The Microstructure And Fracture Behavior Of Low And Medium Carbon Structural Steels, Ignatius C. Okafor, Ronald J. O'Malley, Kaushal R. Prayakarao, Heshmat A. Aglan

Ronald J. O'Malley

Microstructure and fracture behavior of ASTM 572 Grade 65 steels used for wind tower applications have been studied. Steels of two carbon level chemistries designed for this grade were used in the study. Fracture toughness of the steels was studied using 3-point bend test on samples coated with zinc and not coated with zinc. Lower carbon steel showed higher resistance to fracture than medium carbon steel after zinc galvanization. SEM study suggests that zinc and zinc bath additives that migrated to crack tips are responsible for the loss in ductility. The phenomenon of Liquid Metal Embrittlement (LME) is suggested to ...


Effect Of Ultrasonic Treatment On The Microstructure And Mechanical Properties Of Al6061 And Composite, Ana S. Exime 2017 Florida International University

Effect Of Ultrasonic Treatment On The Microstructure And Mechanical Properties Of Al6061 And Composite, Ana S. Exime

FIU Electronic Theses and Dissertations

In this study, the effect of ultrasonic treatment (UST) parameters such as amplitude, sonication time, and melt temperature on microstructure and microhardness of Al 6061 alloy is evaluated. The effect of UST on the dispersion of tungsten disulfide (WS2) and carbon nanotubes (CNT) as reinforcement particles in Al 6061 during casting is also studied. The cast Al 6061 with UST demonstrated 32% grain size reduction and 8% increase in the microhardness for optimum processing conditions. The cavitation process induced by UST is responsible for the refinement in microstructure and increase of hardness by enhancing the degassing and nucleation process ...


Gamma-Radiation Induced Corrosion Of Alloy 800, Mojtaba Momeni 2017 The University of Western Ontario

Gamma-Radiation Induced Corrosion Of Alloy 800, Mojtaba Momeni

Electronic Thesis and Dissertation Repository

This thesis presents a newly developed mechanism and predictive model for the corrosion of Alloy 800. The Fe-Cr-Ni Alloy (Incoloy 800) is mainly used for steam generator (SG) tubing in CANDU and PWR reactors and is a candidate material for the proposed Canadian Supercritical Water Reactor (SCWR) in which it will be exposed to extreme conditions of high radiation flux and large temperature gradients. The influence of gamma radiation and water chemistry conditions on the corrosion behaviour of Alloy 800 are studied in this work. Ionizing radiation creates reducing (•eaq, •H, •O2-) and oxidizing radiolysis (•OH, H2 ...


Coexistence Of Type-Ii Dirac Point And Weak Topological Phase In Pt 3 Sn, Minsung Kim, Cai-Zhuang Wang, Kai-Ming Ho 2017 Ames Laboratory

Coexistence Of Type-Ii Dirac Point And Weak Topological Phase In Pt 3 Sn, Minsung Kim, Cai-Zhuang Wang, Kai-Ming Ho

Ames Laboratory Accepted Manuscripts

Intriguing topological phases may appear in both insulating and semimetallic states. Topological insulators exhibit topologically nontrivial band inversion, while topological Dirac/Weyl semimetals show “relativistic” linear band crossings. Here, we report an unusual topological state of Pt3Sn, where the two topological features appear simultaneously. Based on first-principles calculations, we show that Pt3Sn is a three-dimensional weak topological semimetal with topologically nontrivial band inversion between the valence and conduction bands, where the band structure also possesses type-II Dirac points at the boundary of two electron pockets. The formation of the Dirac points can be understood in terms of the representations of ...


Cu Substituted Ceco5: New Optimal Permanent Magnetic Material With Reduced Criticality, Rajiv K. Chouhan, Durga Paudyal 2017 Ames Laboratory

Cu Substituted Ceco5: New Optimal Permanent Magnetic Material With Reduced Criticality, Rajiv K. Chouhan, Durga Paudyal

Ames Laboratory Accepted Manuscripts

A comprehensive theoretical prediction using a mechanism of site substitution confirms the crucial role of Cu in enhancing the capabilities of CeCo5 as a competitive magnet with its known high coercivity. A remarkable enhancement of magnetic anisotropy energy (MAE) of 3.09 meV/f.u. and 2.94 meV/f.u. without significant decrease of magnetic moment is found for 10% and 5% Cu substitution at 2c sites of the hexagonal lattice. Calculations predict the increment of coercivity and magnetocrystalline anisotropy (1.6 times) compared to pristine CeCo5. The exceptional enhancement in MAE is due to the formation of asymmetric ...


Controlling Magnetism Via Transition Metal Exchange In The Series Of Intermetallics Eu(T1,T2)5in (T = Cu, Ag, Au), Anja-Verena Mudring, Volodymyr Smetana, Vitalij K. Pecharsky, Yaroslav Mudryk 2017 Stockholm University

Controlling Magnetism Via Transition Metal Exchange In The Series Of Intermetallics Eu(T1,T2)5in (T = Cu, Ag, Au), Anja-Verena Mudring, Volodymyr Smetana, Vitalij K. Pecharsky, Yaroslav Mudryk

Ames Laboratory Accepted Manuscripts

Three series of intermetallic compounds Eu(T1,T2)5In (T = Cu, Ag, Au) have been investigated in full compositional ranges. Single crystals of all compounds have been obtained by self-flux and were analyzed by single X-ray diffraction revealing the representatives to fall into two structure types: CeCu6 (oP28, Pnma, a = 8.832(3)–9.121(2) Å, b = 5.306(2)–5.645(1) Å, c = 11.059(4)–11.437(3) Å, V = 518.3(3)–588.9(2) Å3) and YbMo2Al4 (tI14, I4/mmm, a = 5.417(3)–5.508(1) Å, c = 7.139(2)– 7.199 ...


Note On The Rate And Energy Efficiency Limits For Additive Manufacturing, Timothy Gutowski, Sheng Jiang, Daniel Cooper, Gero Corman, Michael Hausmann, Jan-Anders Manson, Timo Schudeleit, Konrad Wegener, Matias Sabelle, Jorge Ramos-Grez, Dusan P. Sekulic 2017 Massachusetts Institute of Technology

Note On The Rate And Energy Efficiency Limits For Additive Manufacturing, Timothy Gutowski, Sheng Jiang, Daniel Cooper, Gero Corman, Michael Hausmann, Jan-Anders Manson, Timo Schudeleit, Konrad Wegener, Matias Sabelle, Jorge Ramos-Grez, Dusan P. Sekulic

Mechanical Engineering Faculty Publications

We review the process rates and energy intensities of various additive processing technologies and focus on recent progress in improving these metrics for laser powder bed fusion processing of metals, and filament and pellet extrusion processing of polymers and composites. Over the last decade, observed progress in raw build rates has been quite substantial, with laser metal processes improving by about 1 order of magnitude, and polymer extrusion processes by more than 2 orders of magnitude. We develop simple heat transfer models that explain these improvements, point to other possible strategies for improvement, and highlight rate limits. We observe a ...


Tunable Dimensional Crossover And Magnetocrystalline Anisotropy In Fe 2 P -Based Alloys, I. A. Zhuravlev, Vladimir P. Antropov, A. Vishina, M. van Schilfgaarde, K. D. Belashchenko 2017 University of Nebraska-Lincoln

Tunable Dimensional Crossover And Magnetocrystalline Anisotropy In Fe 2 P -Based Alloys, I. A. Zhuravlev, Vladimir P. Antropov, A. Vishina, M. Van Schilfgaarde, K. D. Belashchenko

Ames Laboratory Accepted Manuscripts

Electronic structure calculations are used to examine the magnetic properties of Fe2P-based alloys and the mechanisms through which the Curie temperature and magnetocrystalline anisotropy can be optimized for specific applications. It is found that at elevated temperatures the magnetic interaction in pure Fe2P develops a pronounced two-dimensional character due to the suppression of the magnetization in one of the sublattices, but the interlayer coupling is very sensitive to band filling and structural distortions. This feature suggests a natural explanation for the observed sharp enhancement of the Curie temperature by alloying with multiple elements, such as Co, Ni, Si, and B ...


Deformation Processed Al/Al2ca Nano-Filamentary Composite Conductors, Charles F. Czahor, Trevor Riedemann, Alan M. Russell, Iver E. Anderson 2017 Iowa State University and Ames Laboratory

Deformation Processed Al/Al2ca Nano-Filamentary Composite Conductors, Charles F. Czahor, Trevor Riedemann, Alan M. Russell, Iver E. Anderson

Materials Science and Engineering Publications

A 48% increase in worldwide energy demand is expected by 2040, which will require expansion of electrical power transmission infrastructure. 1 Expanded long-distance transmission grids in China, the United States, and elsewhere are expected to make greater use of high-voltage direct current (HVDC) transmission, the preferred technology for long distances.2 Conventional aluminum- conductor steel-reinforced (ACSR) cables are not well suited for HVDC transmission due to the presence of the heavy, poorly conducting steel core needed for strength and sag-resistance. Al/Ca composite conductors with monolithic construction produced by powder metallurgy and deformation processing have shown promise as a possible ...


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