MS&T'11 Poster Session: Fundamentals and Characterization
Program Organizers: Chris Wood, TMS
Tuesday 11:00 AM
October 18, 2011
Room: Exhibit Hall C
Location: Greater Columbus Convention Center
098 3D Simulation of Sliding on Diamond-Coated Carbide Substrates: Kevin Chou1; 1University of Alabama
In this study, a finite element simulation of sliding on a diamond coating deposited on a carbide substrate was applied to investigate dominant factors to coating delamination. Different parameters including coating thickness, elastic modulus of the coating, fracture energy of the interface, and indentation depth have been arranged for a 2-level factorial design with a constant load during sliding process. Minitab was employed to analyze the individual and interaction effects of the parameters from the simulation results. The results show that the fracture energy has the most significant effect on the crack width and length. In addition, the crack width is more sensitive to other parameters at a lower fracture-energy value. The coating elastic modulus has little effect on the crack length and crack width. The interaction between the coating thickness and the indentation depth has a dominant effect on the crack width and crack length.
099 A Triple Junction Distribution Function: Graden Hardy1; David Field1; 1School of Mechanical and Materials Engineering, Washington State University
Triple junctions are one of the fundamental components of polycrystalline microstructure. Triple junction character is responsible for material behavior in relation to grain boundary and triple junction specific phenomena. By characterizing triple junctions microstructural topology and behavior may be better understood and materials with enhanced properties developed. A triple junction distribution function is generated for triple junctions with a coherent twin boundary. This function is obtained through stereological sampling techniques and provides triple point grain misorientations, dihedral angles, and line directions with respect to a crystalline reference frame.
100 Adsorption of Pentacene on Silica Surfaces: An Ab Initio Study: Xiao Ma1; Hossein Hashemi1; John Kieffer1; 1University of michigan
There has been a considerable number of experimental studies on the adsorption of pentacene on substrates for fabricating various electronic devices. The structural and electronic properties of a pentacene adsorbed on silica surfaces have been studied using density-functional theory calculations. First, we investigate the bulk properties of silicon and silica and pure Si(111) and SiO2(111) surfaces. The structural relaxation, work function, and surface energy for the surfaces, as a function of thickness, will be discussed. The mentioned properties of pentacene adsorbed on the silica surfaces will be compared to those of an isolated pentacene molecule. Factors affecting the molecule orientation, such as interface dipole and different binding configurations will be identified. The understanding of the interplay between molecule-molecule and molecule-substrate interactions derived from our calculations provides guidance for substrate preparation and the control of pentacene film growth.
101 Atomistic Modeling of Dislocation-Interface Interactions: Jian Wang1; 1Los Alamos National Laboratory
The atomic structure of interfaces defines their properties. Geometric characters of habit planes mainly determine the characteristic of interface structures. Two geometric factors are chosen to classify interfaces: compact plane and compact direction. Using atomistic simulations we studied the characteristics of the five types of interfaces. Comparing the results among the five types of interfaces, we can conclude that (1) the interface plane is flat when one or two of the two habit planes is a compact plane. (2) The interface contains an array of interface disconnections when the compact directions in both crystals are parallel.(3) The interface plane becomes faceted when the compact directions in both crystals are parallel. (4) The interface plane is flat and composed of coherent and incoherent regions when atomic structures of unit cell in both crystals are similar. We then study the interfacial shear response and further simulate the dislocation-interface interactions.
102 Characterisation and Modeling CuCrZr Electrode Degradation during Resistance Spot Welding: Elise Gauthier1; Denis Carron1; Philippe Pilvin1; Philippe Rogeon1; Cédric Pouvreau1; Jacky Soigneux2; Thomas Lety2; François Primaux3; Christophe Meuret3; 1University of South Britanny; 2PSA Peugeot-Citroën; 3Le Bronze Industriel
Resistance spot welding (RSW) is the main method to assembly auto body. The use of high strength zinc-coated steels in automotive applications leads to the reduction of the electrode life. Even if electrode deterioration is a well-known problem, the understanding and modeling of the complex degradation modes is still limited. Developing a comprehensive thermo-electrical-metallurgical-mechanical model that describes the sequential deterioration is necessary. Microstructural evolution modeling in age hardened CuCr1Zr electrode alloy in welding conditions has been achieved first. Physical properties and constitutive mechanical model, strongly coupled with microstructural phenomena, are then characterized. Finally numerical results obtained by finite element analysis are compared to experimental measurements issued from tests with large quantities of welding spots. A specific attention is paid to the modeling of contact (electrode/sheet and sheet/sheet) and boundary (water cooling) conditions. Using the numerical model, a sensitivity study is made to highlight the main parameters affecting electrode degradation.
103 Effect of Alumina in Phase Formation at the Interface between Titanium and Calcia-Zirconia Composites at 1600℃: YI-EN SU1; MING-WEI LU1; HUAN-TE SU1; SHEN-HUNG WEI1; CHIEN-CHENG LIN1; 1National Chiao Tung University
The samples with various components of Al2O3 were hot pressed with equal ratio CaO/ZrO2 at 1300℃ for 30 min (30MPa) and reacted with titanium at 1600℃/30 min. The specimens of Al2O3/CaO/ZrO2 composite were characterized by X-ray diffraction (XRD) and the interfacial microstructures were observed by scanning emission microscopy (SEM/EDS). The XRD results indicated that there were CaZrO3, c-ZrO2 and CaAl2O4 phases in the specimens. In addition, the proportion of CaZrO3 phase was decreased with Al2O3 in the composite, but that of c-ZrO2 was in the opposite manner. According to SEM observations, there were not numerous reaction layer in the sample which is high component of CaZrO3 but others were. It means Al2O3 play an important role in the proceeding of composite and the reaction between composite and titanium. In conclusion, CaZrO3 could suppress the diffusion of oxygen atoms to titanium.
104 Effect of CaZrO 3 Content on the Interfacial Phenomenon between Titanium and Zirconia at 1400℃: Ming-Wei Lu1; Chien-Cheng Lin1; Huan-Te Su1; Shen-Hung Wei1; 1National Chiao-Tung University
Various CaO/ZrO2 as sintering sample was reacted with titanium at 1400℃/3hr in argon. Investigation CaZrO3 content can be effective to control the interfacial reaction. The microstructure of the reaction interface was characterized using x-ray diffraction(XRD) and scanning electron microscopy(SEM/EDS). The reaction of ceramic side tends to produce CaZrO3 between Ti and 35 mol% CaO/ZrO2 at 1400℃. When zirconium atoms and oxygen atoms simultaneously diffusion to the titanium side. The zirconium atoms will slow down the oxygen atoms diffusion into the titanium side. Prevention the phase formation among titanium side and ceramic side not to be fast. According to the results, the 35 mol% CaO/ZrO2 will be effective than the other components to generate CaZrO3. The more amount of the CaZrO3, the more effectively block titanium atoms, zirconium atoms and oxygen atoms interdiffusion.
105 Effect of Fluorine Incorporation on the Structures and Magnetic Properties of Perovskite and Ruddlesden Popper Ferrates: Peter Slater1; Cathryn Hancock1; Frank Berry1; 1University of Birmingham
Fluorination of Sr3Fe2O7-x and (Sr/Ba)FeO3-x by heat treatment with polyvinylidine fluoride (PVDF) gives a range of novel oxide fluoride compounds, which have been analysed by X-ray diffraction and 57Fe Mössbauer spectroscopy. For the perovskite systems, the fluorination leads to complete filling of the anion sites, the reduction of Fe to Fe3+ and the appearance of magnetic ordering. For Sr3Fe2O7-x, fluorine incorporation leads to a very large expansion in the unit cell volume due to occupancy of interstitial sites within the structure. The O/F distribution in each system will be discussed in detail.
106 First-Principles Study of Reactive Elements Segregation at Grain Boundaries in Chromia: Huazhi Fang1; Zikui Liu1; Paul D. Jablonski2; 1The Pennsylvania State University; 2National Energy Technology Laboratory
It is known that the chromium oxide scale provides a good protectiveness to various Cr-containing alloys, such as the Fe-Cr based stainless steel and Ni-Cr based superalloys, and the doping of certain reactive elements has demonstrated significant improvement on the oxidation resistance of these alloys at elevated temperatures. In current work, the doping effects of reactive elements (Ce, Hf, La, Y, Zr) on the structure and energetics of grain boundaries in chromia have been studied in detail by the first-principles approach. Our calculation results show that the doping elements have a tendency to segregate into grain boundaries and lower the grain boundary energies, and the segregation energies are found to be proportional to the ionic radius and grain boundary complexity. The segregation mechanism was further analyzed in view of the influence of dopants on the atomic and electronic structures of grain boundaries.
107 Floating-Zone Growth and Characterization of Single Crystals of Transition Metal-Containing Orthosilicates
: Qi Tang1; Ruediger Dieckmann1; 1Cornell University
To better understand defects and orientation-dependent transport of transition metal-containing orthosilicates, single crystals of cobalt orthosilicate, Co2SiO4, and manganese orthosilicate, Mn2SiO4, were grown along the three principle axes by using the floating-zone method. Good quality single crystals of high purity cobalt silicate were successfully grown in air at atmospheric pressure. The grown crystals were 30-60 mm in length and 6-10 mm in diameter. Well developed facets were found on all crystals grown. Impurity levels and the degree of a desired excess of silica in grown crystals were determined by using the ICP-AES technique. The presence of inclusions in grown crystals due to a small excess of silica was confirmed by TEM. Dislocation densities were determined upon etching to be on the order of 10 5 to 10 6 cm-2. Crack-free single crystals of Mn2SiO4 were also successfully grown. Results from characterization work on Mn2SiO4 single crystals will also be presented.
108 Geometrical and Topological Evolution in 3D Grain Coarsening of High Purity Nickel Using High Energy X-ray Diffraction Microscopy: S.F. Li1; C. Hefferan2; J. Lind2; U. Lienert3; R. Suter2; A. Rollett4; 1Carnegie Mellon University; 2Carnegie Mellon University, Department of Physics; 3Argonne National Lab, Advanced Photon Source; 4Carnegie Mellon University, Department of Material Science and Engineering
Statistically significant observations of grain boundary motions and topological changes in three-dimensional grain coarsening has been an elusive goal. This is due mainly to the lack of capability in simultaneously probing large numbers of grains non-destructively while being able to maintain the necessary resolution for grain boundary and curvature extraction. Recent advances in High Energy X-ray Diffraction Microscopy (HEDM) (Hefferan et al, this conference) has led to several microstructure experiments where features such as grain boundaries and dislocation densities are tracked across multiple states. In this talk, we will provide an overview of the most recent results in experimental observation of three-dimensional curvature driven grain growth in high-purity Nickel. Our results will be compared with the MacPherson-Srolovitz relations and computational studies from Olmsted et al. Topological events where grains disappear will be illustrated, and effects of anisotropy will be examined. Support: NSF Metals/Nanostructures,DMR-0805100; SFL, JL: DOE/BES,DESC0002001; Advanced Photon Source: DOE/BES,DE-AC02-06CH11357.
109 Grain Boundaries in Dense Nanocrystalline Zirconia and Ceria Ceramics: Exclusive Pathways for Proton Conduction at Room Temperature: Hugo Avila-Peredes1; Chien-Ting Chen2; Shizhong Wang2; Roger de Souza3; Manfred Martin3; Zuhair Munir2; Sangtae Kim2; 1Universidad Autonoma Metropolitana; 2University of California, Davis; 3RWTH Aachen University
Low temperature (30-200°C) protonic conduction in nanocrystalline Gd-doped ceria ceramics with average grain size of ~15nm was investigated as a function of dopant concentration under wet atmosphere. It was found that the proton conductivity of these solid electrolytes was independent of the dopant concentration whereas the oxygen-ion conductivity displayed the expected dependence. These results demonstrated that the proton conduction is independent of the bulk defect chemistry, and thus are consistent with our earlier findings that the proton conduction in the nanocrystalline solid electrolytes takes place exclusively along the grain boundaries. Furthermore, our results strongly suggest that these phenomena may also take place in materials with sufficiently large interfacial/surface areas regardless of the bulk electrical characteristics.
110 Grain Boundary Character Distributions in Severe Plastic Deformed Pure Cu: Hae Jin Lee1; Han Sol Kim1; Won Yong Kim1; Hyun Taek Son1; Kuk Hyun Song1; 1Korea Institute of Industrial Technology
The present study was carried out to evaluate the grain boundary character distributions (GBCDs) due to severe plastic deformation (SPD). Cross roll rolling (CRR) as a SPD method was introduced, and pure Cu (4N grade) sheets as an experimental material was chosen. Pure Cu sheets were cross roll rolled to 90% in thickness reduction and subsequently annealed at 400℃ for 30 min to obtain the fully recrystallized microstructure. For annealed Cu, electron back-scattered diffraction (EBSD) analysis was carried out to investigate the GBCDs. CRR process was more effective to develop the grain refinement, as a result, grain size was refined to 6.5 μm from 100 μm (initial material). Also, grains with <111> crystal direction were densely distributed in microstructure. These grain refinement and texture distribution with component of <111> affect the mechanical properties improvement such as yield and tensile strengths.
111 Grain Boundary Electrical Properties of Ge-Doped Nd4 Ga2 O9: Hirepan Chávez-Cárdenas1; Hugo Avila-Paredes1; 1UAM-I
Based on the high conductivity values of Nd4 Ga2 O9, a cuspidine-type conductor, it has been proposed as a good candidate as solid electrolyte in Intermediate Temperature-Solid Oxide Fuel Cells. Solid solutions of Nd4 Ga2 O9 and GeO 2 have shown superior conductivities. The aim of this work is to determine the correlation of the grain boundary electrical conductivity with the dopant (Ge) content (0 - 20 mol %). Samples were synthesized via a solid state reaction and a citration routes. Powders were compacted and pellets were prepared using conventional sintering. The structure of the samples was verified using X-ray diffraction and the average grain size of the samples was estimated based on scanning electron microscopy images. Impedance spectroscopy measurements of the samples were made under air to determine the contributions of the bulk and the grain boundary conductivities to the overall conductivity of the materials.
112 Grain Growth in Copper, Copper-Titanium, and Titanium Doped Alumina: Abigail Lawrence1; 1Lehigh University
Little work has been done to relate the known wetting behaviors to the sintering and grain growth in alumina doped with copper, copper-titanium, and titanium. A systematic study has connected the wetting of copper, titanium, and copper-titanium alloys on polycrystal alumina to grain growth when sintered in atmospheres varying from highly reducing to ambient. The results from a preliminary study on these systems along with established wetting behavior were used as a starting point for the parameters selected. The varying degrees of wettability along with the influence of different atmospheres were compared side by side. The results take us one step further in understanding how grain growth is controlled and influenced by complexions.
113 Image Analysis Investigating Porous Structures of Carbon Cathodes Materials and Penetration of Cryolitic Melts: Xiang Li1; Jilai Xue1; 1Unversity of Science and Technology Beijing
Carbon cathodes are porous materials for use in aluminum reduction cells. Image analysis has been applied to characterize their porous structures with respect to the penetration of cryolitic melts at elevated temperatures. It was found the micro-pores orientation and connectivity showed strong correlation with the amount of penetrated melts among various cathode materials. This correlation can be explained in association with the quantitative information of the porous parameters and degree of graphitization for the cathodes materials. The obtained information in this investigation can be useful to improve the quality of cathode products and the performance of aluminum reduction cells.
114 Improvement of Grain Refining in Severe Plastic Deformed Ni-Cr Alloy: Kuk Hyun Song1; Han Sol Kim1; Won Yong Kim1; 1Korea Institute of Industrial Technology
In order to evaluate the grain refining due to severe plastic deformation (SPD), this work was carried out. Conventional rolling (CR) and cross roll rolling (CRR) as a SPD method were introduced, and Ni-20Cr alloy as an experimental material was chosen. The materials were cold rolled to 90% in thickness reduction and subsequently annealed at 700℃ for 30 min to obtain the recrystallized microstructure. For annealed materials, electron back-scattered diffraction (EBSD) analysis was carried out to investigate the grain boundary characteristic distributions (GBCDs). CRR process was more effective to develop the grain refinement than that of CR, as a result, grain size was refined to 4.2 μm (CR) and 2.4 μm (CRR) from 70 μm (initial material). These grain refinements directly affect the mechanical properties improvement, in which microhardness and yield and tensile strengths were significantly increased than those of initial material.
115 Interface Microstructure and Mechanical Properties of Steel/Mg Alloy Multilayered Metal Composites by Infiltration: Shoichi Nambu1; Masaki Koba1; Junya Inoue1; Toshihiko Koseki1; Arda Cetin2; Andreas Rossoll2; Andreas Mortensen2; 1The University of Tokyo; 2EPFL
Multilayered metal composites consisting of steel and Mg alloy are fabricated by infiltration, and the microstructure at the Mg/steel interface and the mechanical properties are characterized. Composites of this investigation combine type 304 stainless steel (SS304) with magnesium alloys ZM21 containing Zn and Mn or AZ63 containing Al and Zn. In SS304/AZ63 composites, a thick intermetallic compound, FeAl, is observed at the interface. No interfacial intermetallic compound is formed in the SS304/ZM21 combination; however, Mn-enrichment is observed near the interface. The toughness of the SS304/AZ63 interface is quite low owing to the thick intermetallic compound at the interface, while that of the SS304/ZM21 interface was high enough for cracks to deviate from the interface into the ZM21 layer. Results demonstrate that microstructures around the interface and mechanical properties are strongly affected by alloying elements of Mg alloys, and that with appropriate alloy compositions, strongly bonded composites can be produced.
116 Interfacial Phase Effect on Static-Dynamic Mechanical Properties of W-Ni-Fe Heavy Alloy: Yong Jin Jeon1; Tae Ho Lee1; Se Hoon Kim1; Young Do Kim1; 1Hanyang University
W-Ni-Fe heavy alloy have been used in various fields such as kinetic energy penetrator, radiation shielding materials, due to their high density and good mechanical properties. In this study, the sintering of W-Ni-Fe alloy with various Ni/Fe ratios was demonstrated to improve mechanical properties and penetration capabilities by formation of interfacial phase. The microstructural changes and the mechanical properties of W-Ni-Fe alloy after liquid-phase sintering were investigated. Each of green body samples were sintered at 1480oC in H2 atmosphere and after that the effects of microstructural changes on mechanical properties was evaluated. Vickers hardness and tensile strength of 95W1.3Ni3.7Fe sample, which had W grains coated by Fe7W6 phase (μ-phase), have higher values than other samples. As a result, enhancement of mechanical properties was considered by uniformly generated μ-phase around W grains.
117 Investigation of the Effect of Molybdenum on Microstructure and Mechanical Properties of High Mn Steel Fe-33Mn-3Si-2Al: reza razavi1; Mohsen Saboktakin1; 1department of materials engineering Islamic azad university, Najafabad Branch, Isfahan, Iran
TWIP steels are a family of high Mn austenitic steels posses both high strength and high ductility among aotumotive body steels. In the present paper, the effect of addition of Mo on improving of mechanical properties of a TWIP steel (Fe-33Mn-3Si-2Al) is investigated. To do this, different amount of Mo were added to the chemical composition of steel and the resulted mechanical properties, microstructure and crystallographic phases were examined after casting, hot rolling and annealing. The results showed that addition of Mo enhances the mechanical properties; however, the optimum strength was obtained by addition of 0.3% Mo. This resulted to a 50% increase to ultimate strength and 40% decrease in grain size.
118 Ligational Aspects of the Mesogenic Schiff-Base, N,N’-di-(4’-Octadecyloxybenzoate) Salicylidene Diaminoethane, with Some Rare Earth Metal Ions: Sanyucta Kumari1; Angad Singh1; T. Rao1; 1Banaras Hindu University, Varanasi
A novel mesogenic Schiff-base, N,N’-di-(4’-octadecyloxybenzoate)salicylidene diaminoethane (H2L4 showing Sm-F and Sm-G mesophases), 1, was synthesized and its structure studied by elemental analyses and mass, NMR & IR spectra. Lanthanide complexes of the Schiff-base with the general formula, [Ln(L4H2)3NO3](NO3)2 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho), were synthesized and structurally characterized; on the basis of IR & NMR spectral data of the complexes the Schiff-base was found to act as a bi-dentate Zwiterionic-species coordinating through two phenolate oxygens. A distorted square anti-prismatic polyhedron was proposed around the LnIII ions. Among the complexes, only that of the La(III) was found to be mesogenic with nematic phase.
119 Measuring Heterophase Interface Character Distribution (HICD) in Accumulative Roll-Bonded (ARB) Cu-Nb Multilayered Composites: Sukbin Lee1; Jonathan LeDonne1; Samuel Lim2; Irene Beyerlein3; Anthony Rollett1; 1Carnegie Mellon University; 2Singapore Institute of Manufacturing Technology, A*STAR Singapore; 3Los Alamos National Laboratory
The full five-parameter heterophase interface character distributions (HICD) in accumulative roll-bonded (ARB) alloyed Cu-Nb multilayer composites are presented. The heterophase interfaces between Cu and Nb are segmented on two-dimensional electron back-scatter diffraction (EBSD) maps using the multi-material marching square algorithm. The segmented interfaces are smoothed subject to the constraint of constant area of each initially segmented individual domain. Three-dimensional heterophase interface normal vectors are then derived from the normals to the smoothed interfaces with certain assumptions. The HICD shows a strong preference for {110}Cu and {112}Cu and {112}Nb planes. The interphase misorientations includes Kurdjumov-Sachs and the preferred normals vary with misorientation type. This result is contrasted with the {111}Cu and {110}Nb normals that are characteristic of physical vapor deposited (PVD) pure Cu-Nb multilayers. Support from the BES-supported CMIME and the NSF-supported MRSEC at CMU is acknowledged.
120 Microsecond-Pulsed High Resolution Glow-Discharge Mass Spectrometer for Multielemental Nanometer Scale Depth Resolved Measurements of Thin Layered Structures: Glyn Churchill1; Xinwei Wang1; Karol Putyera1; 1Evans Analytical Group, LLC.
A highly sensitive analytical test method has been successfully developed for measuring trace element distributions in multilayered thin film structures with atomic layer depth resolutions. It is based on a new µs-pulsed dc supply assembly, which is installed on a fast flow high power GD source and attached to a high resolution mass analyzer. This new assembly allows atomic layer determination of trace impurities at the boundary interfaces of thin layered structures such as photovoltaic films, with significantly improved signal/noise ratios.
120 Numerical Simulation of Solidification Structure of 28MnCr5 Gear Steel during the Continuous Casting Process: Suzhou Wu1; Zhizheng Li2; 1Wuhan University of Science and Technology; 2University of Science and Technology Beijing
28MnCr5 is a kind of advanced gear steel. Its internal quality is closely related with its solidification structure. During the production process of continuous casting, the relationship between solidification structure and actual parameters has been investigated. At the same time, according to the actual casting process smelting 28MnCr5 parameters, using ProCAST software and CAFE model to simulate the solidification.The results show that when the superheat increases from 10℃ to 40℃, the grain density increases from 6.911×106m-2 reduced to 4.133×106m-2, the average grain surface area increases from 1.447×10-7m2 to 2.419×10-7m2, maximum grain surface area from 4.9×10-7m2 increased to 3.56×10-6m2, and the average grain radius increases from 269.4μm to 410.2μm. Due to the solidification of steel 28MnCr5 gear and internal quality requirements, the superheat should be reduced as far as possible when other conditions were met.
122 Oxygen Transport and Oxidation States of B-Site Cations in Ba(Co, Fe, Nb)O3-δ: Jianxin Yi1; Jochen Brendt1; Michael Schroeder1; 1RWTH Aachen
Oxygen nonstoichiometry and diffusivity are two key factors governing the oxygen transport of mixed-conducting oxides. Both properties are closely related to the structure and chemical composition. The oxygen nonstoichiometry can be derived from the oxidation states of the transition metals in the perovskites, whereas the oxygen diffusivity is reflected by the oxygen permeability. In this work, structural variations, transition metal oxidation states, and oxygen permeation fluxes of Ba(Co,Fe,Nb)O3-δ were investigated with XRD, XANES, and oxygen permeation measurements. Substitution of Fe for Co results in a smaller lattice constant, whereas Nb substitution leads to the opposite trend. The oxidation state of cobalt is smaller than 3+ and increases slightly as its content decreases; whereas the oxidation states of iron and niobium are close to 3+ and 5+, respectively, and are almost independent of the composition. Increasing the iron and niobium content leads to a diminished oxygen nonstoichiometry and oxygen permeability.
123 Power and Gas Pressure Effect on the Properties of Amorphous In-Ga-ZnO Thin Films by Magnetron Sputtering: Yuanjie Li1; Xiaofen Hu1; Zilong Liu1; Jiangbo Ren1; 1Xi'an Jiaotong University
We deposited In-Ga-ZnO (IGZO) thin films on quartz glass at room temperature using radio frequency magnetron sputtering. X-ray diffraction shows IGZO thin films have amorphous structure. Hall effect measurement reveals that the carrier concentration is 9×1019 cm-3 and Hall mobility is 16.8 cm2/Vs in the IGZO films grown at 500 W sputtering power. It is shown that the Hall mobility of IGZO films increases with sputtering power. Average optical transmittance of IGZO films is greater than 80%. The as-grown IGZO films is being annealed in flowing H2/Ar at 500 ℃ for 1 hr. X-ray photoelectron spectroscopy valence band spectrum is being used to characterize the energy state in the as-grown and hydrogen-annealed IGZO films. The effect of sputtering power and oxygen partial pressure as well as hydrogen annealing process on Hall mobility, structural and chemical properties is being investigated and will be discussed in this study.
124 Predicting Grain Boundary Structures and Properties from AB Initio Molecular Dynamics and First-Principles Calculations: William Wang1; H.Z. Fang1; S.L. Shang1; Y. Wang1; S. Mathaudhu2; Z.K. Liu1; 1Penn State University; 2US Army Research Office
A solid-liquid interface model is developed to predict grain boundary structures through ab initio molecular dynamic calculations. Using the coincidence site lattice model for Cu, the twinning ∑3[011](1-11) and ∑5[001](210) grain boundary structures are created and their related energies from our calculations match well with the previous reported results. Additionally, entropy, enthalpy and heat capacity of these grain boundaries are studied in terms of quasiharmonic approach with the vibrational contribution to Helmholtz free energy described by the Debye model. The newly developed approach is used to predict the grain boundary structures with arbitrary orientations.
125 Quantifying the Effect of Spatial Resolution on the Accuracy of 3-D Feature Characterization: Gregory Loughnane1; Ramana Grandhi1; Raghavan Srinivasan1; Michael Uchic2; Michael Groeber2; Matthew Riley3; Megna Shah4; 1Wright State University; 2Air Forece Research Laboratory; 3University of Idaho; 4UES Inc
The choice of spatial resolution for experimentally-collected three dimensional (3D) microstructural data is often governed by general rules of thumb based on ad hoc estimates of fidelity requirements. For example, in serial sectioning experiments it is generally accepted that one would like a minimum of 10, but preferably at least 20 sections through a microstructural feature to accurately describe its size and shape. However, the desire to collect high resolution serial section data is tempered by the cubic growth in collection time with increasing spatial resolution. This work aims to quantitatively determine the minimum number of sections relative to the mean feature size to achieve a user-defined accuracy for selected characterization parameters such as the equivalent sphere diameter (for both the mean as well as the full distribution). State-of-the-art 3D materials analysis software, DREAM.3D, is used to generate synthetic (digital) microstructural volumes from user-supplied statistical input distributions for morphological parameters. The uncertainty in selected characterization parameters as a function of spatial resolution is determined via virtual down-sampling of the digital microstructure, and comparing this data relative to the original reference volume.
126 Residual Compressive Stress Concentrations in Pb-Free Solders: Benjamin Anglin1; Wei-Hsun Chen2; Pylin Sarobol2; RA Lebensohn3; AD Rollett1; JE Blendell2; CA Handwerker2; 1Carnegie Mellon University; 2Purdue University; 3Los Alamos National Laboratory
Tin whiskers from Pb-free solders have been studied extensively, yet their growth mechanisms remain a challenge to understand. Compressive stresses have been theorized to promote tin whisker growth in Pb-free solders with the aid of diffusional creep. These compressive stresses may result from thermal expansion anisotropy and thermal fluctuations, and therefore, full-field solutions will be computed for microstructures representative of Pb-free solder using a thermoelastic fast Fourier transform method. Two planar micro-diffraction measurements were made on electroplated Sn-Cu films on Cu substrates and used to synthetically construct separate nearly columnar microstructures. The stress distributions and the differences between the two microstructures will be discussed.
127 Structural Aspects and Li Ion Conductivity of Cation Excess Garnets: Peter Slater1; Julia Percival2; 1University of Birmingham; 2University of Surrey
Garnet oxides have ideal formula A3B2C3O12 (A, B, and C can be a range of cations) , and have attracted significant interest for a range of applications. Recently new Li containing garnets have been reported which display high Li ion conduction. Such materials have the general formula A3B2Li3+xO12, with x varying between 0 and 4. As such, compared to the ideal garnet materials, these materials contain cation (lithium) excess. In this poster, research on a range Li ion conducting garnets will be discussed, examining the effect of Li content on the structure and conductivity. In addition the stability of these systems towards humidity will be discussed, showing the possibility for Li/H exchange.
128 Structural Optimization of Multilayered Barrier Films Using Numerical Simulation: Sangil Hyun1; Soojung Kim1; Eunhae Koo1; Youngsoo Lim1; Seung-Hun Huh1; 1Korea Institute of Ceramic Engineering & Technology
We employed numerical simulations to determine optimal structures for the multilayered barrier films for water vapor protection. The barrier films are organic/inorganic multilayered structures. The vapor permeates through the percolated cracks in the inorganic film (e.g. alumina). The cracks are initiated by the interfacial failure and can grow by iterative bending or thermal loads. It is then highly important to prevent the surface failure to enhance the barrier performance. In this study, we employed finite element method to design the geometry of the barrier films for optimal interfacial strength under various deformations. Sensitivity analysis on the interfacial defects were performed for the optimized structures. Experimental observation on the interfacial failure is also presented to verify the simulation results.
129 Study of Mechanical Deformation of Zr55Cu30Al10Ni5 Bulk Metallic Glass through Instrumented Indentation: Mohammad Marvi-Mashhadi1; Abolfazl Rezaee-Bazzaz1; Mohsen Haddad-sabzevar1; 1department of material science & engineering, ferdowsi university of mashhad
Instrumented sharp indentation experiments using both Vickers diamond pyramid and conical indenters were carried out to study deformation characteristics of Zr55Cu30Al10Ni5 bulk metallic glass. Finite element simulations of instrumented indentation were also carried out to formulate an overall constitutive response. Comparing the experimentally observed indentation results with the finite element predictions, it can be said that mechanical deformation of the bulk metallic glass can be described well by both Mohr-Coulomb and Drucker-Prager constitutive criteria. Using these criteria, location of circular patterns of shear bonds observed around indenter, their size and shape can also be well predicted. Both Mohr-Coulomb and Drucker-Prager constitutive criteria are also able to estimate the extent of material pile-up observed around indenter, very well.
130 Synthesis and Characterization of Partially Stabilized Zirconia by Doping with CaO and MgO: Pat Nandakumar1; Elvira Nieto1; 1University of Texas of Permian Basin
The synthesis of Partially Stabilized Zirconia doped with CaO and MgO to produce a high toughness ceramic using different percentage compositions of each. The process was carried out by mixing Zirconiumoxychloride, calcium oxide and dissolving with nitric acid, followed by the addition of citric acid, and ammonium hydroxide. The solutions were then heated in an open air oven at 350°C for an hour. The solutions were then heated at 700⁰C in the same open air oven for another hour. Each sample was characterized by X-ray diffraction analysis, and X-ray fluorescence. The temperature dependent studies of crystalline structure are studied using D8 X-ray Diffractomer and TTK450 accessory. Doping with CaO provides a stability and increased toughness for the Partially Stabilized Zirconia by allowing the crystal phase to change from monoclinic phase to its tetragonal, rhomboid, and cubic phase. Zirconia doped with CaO will also have reduced conductivity and high capacitance.
131 TEM Characterization of the Basal Screw Dislocation in a (0001) Low-Angle Twist Grain Boundary of Alpha-Al2O3: Eita Tochigi1; Naoya Shibata1; Atsutomo Nakamura2; Takahisa Yamamoto1; Yuichi Ikuhara1; 1The University of Tokyo; 2Osaka City University
An alpha-Al2O3 bicrystal including a (0001) / [0001] low-angle twist grain boundary was fabricated by bonding two single-crystal substrates at 1500 oC for 10 hours in air. A sample for transmission electron microscopy (TEM) which includes the grain boundary parallel to the surfaces was prepared with great care by mechanical and Ar+ ion milling. The grain boundary structure was extensively observed by conventional TEM. It was found that the grain boundary consisted of band-like structures and hexagonal dislocation networks. The band-like structures arrayed parallel with each other and probably accommodate a mistilt component of the boundary due to slight miscut of the initial substrates. The g.b analysis revealed that the dislocations formed the hexagonal networks are 1/3<1-210> basal screw dislocations, which can accommodate a twist component. In the presentation, we will also demonstrate the core structure of the basal screw dislocations by end-on high-resolution TEM observation.
132 The Characterization of Polypropylene Nanoclay Composite: Mohamad Nor Berhan1; Anizah Kalam1; 1UNIVERSITI TEKNOLOGI MARA
The polypropylene nanoclay composite was investigated in this study.The understanding of polypropylene nanoclay is of interest because it allows us to monitor the mechanical properties developed or changes as a result of loadings. The propylene characteristics were carried out in term of tensile strength, flextural modulus , elongation at break and impact strength . Further investigation on the behaviour of the composite were also carried out using the thermogrametric and the X-Ray diffraction for crystallography. In order to understand the relation between properties and surface morphology at the nanoscale the Atomic Force Measurement were made. The rsults were discussed in term of properties and the structures that exist.
133 The Effect of Heat Treatment on the Mechanical Properties of AZ80 Alloy: Ran Liu1; Jing Tao Wang1; Deliang Yin1; 1Nanjing University of Science and Technology
The effect of aging temperature and time on precipitates in AZ80 magnesium alloy was studied by scanning electron microscope (SEM) to investigate the change on mechanical properties. The results show that precipitate distributed as braid along the extruded direction with no twinning. After aging, precipitate discreted. When ageing at 150℃, discontinues precipitates phase could increase the yield and tensile strength but not good to the ductility of the material. Ageing at 300℃, with the increase the aging time, static ductility increase first and then decrease. That means recrystallization induced by continues precipitate is benefit to the strength and ductility. The microstructure of yield stage was observed that twinning activate in 300℃ ageing but not found in 150℃ sample. And twinning also activated in compression much more than in tensile samples, that’s the same as in AZ31 alloy.
134 Thermal Polarization and Characterizations of Polyimide/TiO2 Samples: Mulayam Gaur1; Ram lal2; 1Hindustan College of Science and Technology; 2Pt. J. L. N. Government College
New organic–inorganic nanocomposite based on polyimide/TiO2 was prepared by solution mixing process and sonification of polymer/TiO2 solutions. The nanocomposite samples were characterized in terms of morphology, structure, dielectric stability before and after polarization. The surface morphology was studies using atomic force microscopy (AFM). It is observed that the surface roughness increases with increase in TiO2 concentration. The Thermally stimulated current (TSC) has been recorded in thermally polarized nanocomposite samples to understand the relaxation mechanism in nanocomposite samples. The results showed that macrovoids were nearly suppressed with formation of a sponge like structure. The TiO2 particles were uniformly dispersed in polyimide. The nanodispersed inorganic network formed after solution mixing and the strong interaction between inorganic network and polymeric chains led to the improvement of thermally stimulated dielectric properties. In particular concentration (i.e. 7%) of TiO2 the dielectric constant increased drastically.
135 Transference Number Measurements of MIECs: SSC and LSGM: Ted Yeh1; Nicola Perry1; Thomas Mason1; Jules Routbort2; 1Northwestern University; 2Argonne National Laboratory
Mixed ionic and electronic conductors (MIECs) can improve the performance of solid oxide fuel cell (SOFC) electrodes through increased efficiency and power output as well as decreased operating temperatures. However, accurate characterization of the minority species’ transference numbers can be difficult using traditional blocking electrode methods. Alternative methods for elucidating transference numbers are presented for highly electronic MIECs (strontium-doped samarium cobaltite, SSC) and highly ionic MIECs (strontium- and magnesium-doped lanthanum gallate, LSGM). This presentation focuses on the determination of oxygen diffusivity in SSC by Secondary Ion Mass Spectroscopy (SIMS) and on AC impedance spectroscopy measurements of electronic versus ionic conductivity in sub-100 nm polycrystalline LSGM. Ramifications for SOFC applications will also be discussed.