Characterization of Minerals, Metals, and Materials: Nano Materials
Sponsored by: TMS Extraction and Processing Division, TMS: Materials Characterization Committee
Program Organizers: Shadia Ikhmayies, Al Isra University; Bowen Li, Michigan Technological University; John Carpenter, Los Alamos National Laboratory; Jian Li, CanmetMATERIALS; Jiann-Yang Hwang, Michigan Technological University; Sergio Monteiro, Military Institute of Engineering ; Firrao Donato, Collegio Universitario, Italy; Mingming Zhang, ArcelorMittal Global R&D; Zhiwei Peng, Central South University; Juan P. Escobedo-Diaz, UNSW Australia; Chenguang Bai, Chongqing University; Eren Kalay, METU; Ramasis Goswami, Naval Research Laboratory; Jeongguk Kim, Korea Railroad Research Institute

Monday 2:00 PM
February 27, 2017
Room: 32B
Location: San Diego Convention Ctr

Session Chair: John Carpenter, Los Alamos National Laboratory

2:00 PM  
Enhanced Physical Properties of Thin Film Nanocomposites: T. Thuy Minh Nguyen1; Sathish Lageshetty1; Paul Bernazzani1; 1Lamar University
    The addition of nanoparticles to epoxy resins often results in changes in the physical properties of the material particularly when dealing with thin coatings. By characterizing the mechanism of interactions between nanoparticles and polymer chains the material could be tailored for specific applications or properties such as enhanced biodegradability. This study compared the characteristics of common DGEBA resin coated on a silicon substrate and embedded with nanoparticles of TiO2, ZnO, and Fe2O3. Specifically we investigated the rate of curing, the thermal stability, the rheological properties, and the biodegradability of these nanocomposites. Results show enhances in curing rates and stability for compounds containing TiO2, while Fe2O3 significantly enhanced the biodegradability of the nanocomposites while maintaining similar physical properties.

2:20 PM  
Grain Size and Mechanical Properties in Severely Rolled Duplex Steel: John Carpenter1; Nan Li1; Rodney McCabe1; Nathan Mara1; Irene Beyerlein2; 1Los Alamos National Laboratory; 2University of California - Santa Barbara
    2205 duplex stainless steel is processed via accumulative roll bonding to obtain a nanocrystalline structure. In this study, a comparison is made in the structure and mechanical behavior of FCC/BCC austenite/ferrite with biphase nanolamellar Cu/Nb studies performed previously. As grain size approaches ~100 nm, it is found that a unique texture develops consistent with Cu/Nb studies. Inconsistent with these same studies, however, is that grain sizes and mechanical properties saturate with increased reductions once grain size approaches ~100 nm. Finally, texture extracted from the interface grains in polycrystalline rolled duplex steel is used to understand the likely interface structure present if a single grain through the layer thickness can be obtained using a rolling process. Explanation of processing steps, site-specific characterization via transmission electron microscopy & precession electron diffraction, site-nonspecific characterization via neutron diffraction, and mechanical testing via tensile & hardness testing will be discussed in this presentation.

2:40 PM  
Effect of Incorporation of POSS into Fluoroelastomer Matrix: Heloisa Zen1; Ademar Lugăo1; 1IPEN
    The effect of inorganic nanoparticle into polymeric matrix is one of the most widely researched now a day. The nanoparticle incorporation improves mechanical and thermal properties, and also gases barrier of the polymer. This incorporation can be facilitated by elastomer solubility, which achieves a homogeneous distribution inside the matrix of the elastomer. In this work was carried out the incorporation of POSS (polyhedral oligomeric silsesquioxane) into fluoroelastomer at 0.5; 1 and 2%, weight. After the nanocomposites obtained, was performed the vulcanization process. The films were characterized by mechanical tests, DMA and swelling in order to determine the modification of the fluorelastomer.

3:00 PM  
A Study on the Size and Type of Inclusions in Si-Mn Combined Deoxidated Low Carbon Steel Strip: Ting Wang1; 1Shanghai University
    The type of inclusions with different sizes in as-cast low carbon steel strip which is deoxidized by Si-Mn has been characterized by scanning electron microscope (SEM) and transmission electron microscopy (TEM). SEM observation and analysis suggested that the type of inclusions larger than 1 μm is manganese silicate. TEM analysis was carried out to investigate the composition and structure of nano-inclusions. Inclusions with diameter about 100 nm are manganese silicate, MnS-Si(Mn)Ox complex particles and isolated cubic Al2O3. Furthermore, HREM observations have revealed that there were two kinds of ultrafine particles in size range of 5-10 nm. One is spherical monoclinic Cu2S; the other is silicon-iron oxide particles with morphology of long strip. In addition, some thermodynamic calculations were performed to explain the corresponding relation between the type of inclusions and their size.

3:20 PM  
To Twin or Not to Twin in Boron Carbide: Kelvin Xie1; Fatih Toksoy2; Vlad Domnich3; James McCauley4; Rich Haber3; Kevin Hemker1; 1Johns Hopkins University; 2Rutgers University ; 3Rutgers University; 4U.S. Army Research Lab
    Boron carbide is an attractive material due to its low density and super hardness. Incorporating nanotwins into boron carbide may further improve the mechanical properties and ballistic performance. Here, we show that nanotwins can be engineered into boron carbide by two novel routes. The first method is to grow nanotwins into the starting B4C powders and then consolidate the powders to achieve dense nanotwinned samples. The second route is to start with twin-free powders and then grow twins during sintering by controlling the chemical stoichiometry. Boron carbide has a wide range of stable phases from B11C to B4C. Extensive planar defects (e.g. stacking faults and twins) were observed in the boron-rich boron carbide (e.g. B6.5C and B8.6C), but were not found in B4C. The origin of “asymmetric twins” in boron carbide will be discussed, and the influence of twins on the hardness and indentation fracture toughness will also be addressed.

3:40 PM Break

3:55 PM  
The Influence of Grain Boundaries and Grain Orientations on the Stochastic Responses to Low Load Nanoindentation in Cu: Benjamin Schuessler1; Pui Ching Wo1; Hussein Zbib1; 1Washington State University
    Mechanical properties in the macro scale are considered to be deterministic, but they have been shown to be stochastic in the sub-micron length scale during nanoindentation. The origin of such stochastic responses is not well understood. The objective of this work is to examine the potential influence of microstructure, in particular grain boundaries and grain orientations, on the stochastic responses in the material during low load nanoindentation. Well-annealed high purity polycrystalline Cu was used in this study. It was found that the pop-in load, displacement excursions at pop-in, hardness and reduced modulus all exhibited different extent of variations. In addition, such stochastic behavior appears to be affected by the grain orientation and the proximity of an indent to a grain boundary. Direct transmission electron microscopy observation of the dislocation structure around nanoindents helps to explain its potential interaction with a grain boundary that may lead to the observed stochastic behavior.

4:15 PM  
Magnetic Property and Core-shell Nanostructure of Ni Nanoparticles Coated on Si3N4 Powders: Huazhang Zhai1; 1Beijing Institute of Technology
    Modifying the surface of Si3N4 grains with metal nanoparticles is critical in approach to enhance their dispersion and endow composite powders with new functions. In the present work, the metal nickel (Ni) nanoparticles are deposited on Si3N4 grains to form Si3N4@ Ni composite powders using electroless plating. The results showed that the catalytic core structure of Sn-Pt was successfully formed on the surface of Si3N4 grains after the activation and sensitization. In the electroless plating process, Ni nanoparticles formed with a size about 5-20 nm, and then grew together to form a continuous nano-coating. The Si3N4 grains with Ni nano-layers were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and High-resolution transmission electron microscope (HRTEM). The magnetic property of Nano-nickel coated Si3N4 powders were also measured by vibrating sample magnetometer (VSM).

4:35 PM  
Dielectric Property, Characterization and Preparation of 3Y-ZrO2/TiO2 Solid Solution Ceramics: Huazhang Zhai1; 1Beijing Institute of Technology
    The 3Y-ZrO2/TiO2 solid solution powders are prepared by chemical precipitation method and explore the appropriate temperature and pH of the experiments. The suitable calcining time and temperature are determined using the DSC-TG analyses. By adding different proportions of TiO2, we discussed the changing process of the solid solution. By using BET, XRD, etc., the products are characterized respectively and explicitly. It proved that as- prepared nanopoweders with high surface area and diameter under 20nm. We also study the optical properties of powders, as a reference for future research. By pressing the nanopowders into template and measuring the microwave dielectric property of the material, we proved that this ceramic is a kind of material with low permittivity and permittivity loss.

4:55 PM  
Effect of Argon Gas Purging of Spark Plasma Sintered ZrB2+SiC Nano-powder Composites: Naidu Seetala1; Owen Reedy1; Lawrence Matson2; HeeDong Lee3; Thomas Key3; 1Gramblimg State University; 2Wright-Patterson Air Force Research Lab; 3UES, Inc.
    Spark Plasma Sintering (SPS) consolidated ZrB2-SiC composites using nano-powders (around 40 nm) showed smaller grains compared to those using micron size powders and segregation of SiC into islands is minimal, but with higher oxidation of ZrB2 to form ZrO2 in nano-composites. Argon-gas purging prior to SPS consolidation at around 2,000°C and 40 MPa of ZrB2-20vol%SiC nano-powders was used to minimize the oxidation and obtain fine granules with high densification. The densification of the Argon-gas purged nano-composites is higher compared to those consolidated without Argon gas purging. The EDX analysis showed a strong reduction in the oxygen peak for the Argon gas purged composites. The XRD spectra also support this observation with less ZrO2 phase composition in Argon gas purged composites. The Vickers micro-hardness showed slightly lower values for Argon gas purged composites though they have higher densification.

5:15 PM  
Stochastic Character of Plastic Deformation in FIB-milled Copper Micropillars Investigated by the Acoustic Emission Technique: Michal Knapek1; Ádám Hegyi2; Péter Ispánovity2; Kristián Máthis1; František Chmelík1; István Groma2; 1Charles University; 2Eötvös Loránd University
    Plastic deformation of micron-scale crystalline materials differs considerably from bulk specimens, as it is characterized by random strain bursts. In this work, copper single-crystalline micropillars of various geometries were fabricated and tested. An improved focused ion beam fabrication method was proposed to get non-tapered micropillars with a maximum control over their shape. Compression tests with concurrent acoustic emission (AE) measurements were used to investigate the stochastic effects that appear in micron-scale plasticity, and to analyze statistical features of collective dislocation phenomena and associated strain bursts. Size effect in the plastic flow stress as well as clear correlations between the strain bursts and the AE events were found even at these small scales and were further statistically evaluated.