General Poster Session: General Poster Session
Sponsored by: TMS Extraction and Processing Division, TMS Functional Materials Division, TMS Light Metals Division, TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division
Program Organizers: TMS Administration
Tuesday 6:00 PM
February 28, 2017
Room: Hall B1
Location: San Diego Convention Ctr
M-1: A Comparison between Quenching and Furnace Cooling after Sintering of Al-4Cu-1.5Mg Alloy: Byungmin Ahn1; SeHwan Lee2; 1Ajou University; 2Ehwa Diamond Industrial Co., Ltd.
In the sintering process of powder metallurgy (P/M) aluminum alloys, the effect of cooling conditions during the sintering cycle has been rarely studied. In the present research, a 2xxx series Al P/M alloy (Al-4Cu-1.5Mg) was sintered and cooled in two distinct rates, furnace cooling and water quenching. After the sintering cycle was completed, both sintered materials were T6 heat-treated for precipitation strengthening. The mechanical behavior was compared between two materials at different processing steps using the Vickers hardness and transverse rupture strength (TRS) tests. The microstructural evolution of two as-sintered materials was investigated using scanning electron microscopy (SEM), and the precipitation morphology of two as-aged materials was characterized using transmission optical microscope (TEM) and energy dispersive spectroscopy (EDS). The results showed the furnace-cooled one exhibited superior mechanical properties compared with the water-quenched one. The comparison was discussed in details in terms of the variation in precipitation behavior.
M-2: Advances in Automated Optical 3D Materials Characterization: Satya Ganti1; Brian Hayes1; Veeraraghavan Sundar1; 1UES Inc.
Advances in automation have made possible the cost-effective collection of three dimensional microstructural information. When optical microscopy is used as a data collection method, the scale of sample analyzed is correspondingly large, as is the variety of materials that can be analyzed using such techniques. 3D materials characterization circumvents the weaknesses inherent in geometric models that are used to estimate distribution functions and topological properties by providing actual data. In this study, Robo-Met.3D, an automated system for 3D materials characterization, is extended to characterize materials properties such as porosity in additively manufactured parts, and in ceramic and organic matrix composites, as well as challenges such as analyzing grain size distribution in aerospace materials. The resulting visualizations provide insights into materials properties and processes.
M-3: Analyzing Polycrystalline Grain Microstructures in Thin Films: Ahu Öncü1; Thomas Hempel1; Bodo Kalkofen1; Thorsten Halle1; Dana Zöllner1; 1Otto von Guericke University Magdeburg
Grain microstructures of polycrystalline solids have an immense impact on materials properties. While it is generally assumed in bulk materials that we are far away from surface areas, in thin films surface effects become important. Grain growth slows down or even comes to a halt, if during grain growth in films the average grain size reaches the order of the layer thickness. Analytic theories of nano- and microcrystalline grain growth are in good agreement with numerical results using computer simulations. However, analytic size distributions or topological correlations between grains rarely capture the experimental features. One reason of this disagreement can be found in the simple fact that the experimental samples are of 3D nature, but are commonly measured in 2D and compared with 2D simulations and analytic theories. In the present work, we analyze the grain microstructures of thin Aluminum films experimentally and compare the results to 3D computer simulations.
M-5: Solving Challenges of Silicon Anodes for Li-ion Batteries: Hallgeir Klette1; Trygve Mongstad1; Hanne Andersen1; Kenneth Knudsen1; Samson Lai1; Jan Petter Maehlen1; Thomas Preston1; Anita Reksten1; Asbjørn Ulvestad1; Martin Kirkengen1; 1IFE (Institute for Energy Technology)
Silicon is, with its high volumetric capacity for storage of lithium ions, considered a natural next step for enhancing the capacity for lithium ion batteries. Silicon can store up to ten times the amount of lithium compared to the standard electrode material of today, graphite, and it can give an increase in capacity on cell level of up to 40%. Battery scientists agree that silicon will be a part of the batteries of the future, and some battery producers are already using a small percentage of silicon in the graphite electrode. This poster presentation will provide insight in how we work on developing the silicon material synthesis methods to achieve high Li-ion battery performance through nano-structuring, coating and alloying. With industrial partners we are also exploring how to maximize the potential of pure silicon by material pre-processing, choosing the optimal electrolyte additives, and control and optimization of the binder systems.
M-6: Densification Mechanism of Fe based Amorphous Alloy Powder during Spark Plasma Sintering: Tanaji Paul1; Sandip Harimkar1; 1Oklahoma State University
Fe48Cr15Mo14Y2C15B6 amorphous alloy powder spark plasma sintered near its glass transition temperature (Tg = 575 oC) at 100 oCmin-1 resulted in enhancement of viscous flow and simultaneous plastic deformation under uniaxial pressure yielding near fully dense samples. Higher temperatures increased stiffening with consequent reduction in densification rate. Sintering at 1000 oC revealed two discrete stages of densification of which the first, taking place by viscous flow upto 585 oC led to a maximum densification rate of 0.0011 s-1. An estimate of the activation energy, 94.0 kJmol-1 appeared smaller than that during non-isothermal viscous flow in the as cast alloy. Investigations with heating rates of 50, 100 and 150 oCmin-1 showed a steady decrease in the temperatures of onset, end and maximum rates of densification as well as in the activation energy for viscous flow from 76.2 to 55.2 kJmol-1.
M-7: Determination of Retained Stress by Jominy Method in Al-Cu Alloys: Ibrahim Hizli1; Burak Tasli1; Eray Erzi1; Derya Dispinar1; 1Istanbul University
Same size of Al-4Cu alloy samples were heat treated at 535ºC. These samples were subjected to Jominy hardenability test method. Different parameters were investigated. Initially, the effect of holding time of 10, 30 and 60 minutes at 535oC was studied. The quenching medium was changed. A static and sprey water application was compared. Additionally, effect of oil quenching was evaluated. Brinell hardness was used to control the change in the hardness along the section of the bars. Thermal analysis was applied to measure the resiual stress. In all samples; resiual stress was higher in the non-quenched edge of the samples than the rapidly quenched side of the sample.
M-8: Development of Cu-Alloy Films for Energy-saving LED Applications: Chon-Hsin Lin1; 1Asia-Pacific Institute of Creativity/Biotechnology
We fabricated a barrierless Cu-alloy film for use as a reliable interconnect. In microelectronic devices, Cu diffuses rapidly into the Si layer, deteriorating the device properties and necessitating a diffusion barrier between Cu and Si to prevent device failure. Furthermore, the synthesized Cu-alloy films remain stable when used as a buffer layer and do not dissolve the solder even when reactions occur at the interface. Our results are expected to facilitate development of innovative low- electrical resistance, low-thermal-resistance, and high-thermal-conductivity metallic materials with good adhesive properties. These materials would be useful in barrierless Cu-metallization energy-saving LED applications. We measured the film resistivity and current–voltage characteristics of the seed layer and assessed the reliability of the seed layer in Cu interconnects by studying the long-term aging characteristics of Sn and Si. The results reveal that the fabricated Cu-alloy film exhibits high thermal stability.
M-9: Direct Conversion of Celestite to SrCO3 by Wet Milling: Raşit Sezer1; Ayşegül Bilen2; İbrahim Göksel Hizli3; Selim Erturk2; Cüneyt Arslan2; 1Karadeniz Technical University; 2Istanbul Technical University; 3Istanbul University
Effect of the high energy ball milling on the direct conversion of celestite to strontium carbonate (SrCO3) was studied. Celestite ore was ground by a planetary ball mill with sodium carbonate (Na2CO3) solution. Experimental study carried out to determine effects of milling time (5, 15, 30, 60, and 120 min) and Na2CO3 concentration (1, 1.25, 1.5, and 2 M) on the precipitation efficiency. Volume of carbonate solution was calculated for the stoichiometric amount of sulfate in celestite and solid material/ball weight ratio is selected 1/10 as constant. After filtering, washing and drying the precipitated SrCO3 sludge was analyzed by X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy. The conversion rate of celestite to SrCO3 increased systematically with extending milling time. The strontium carbonate in the product can be concentrated up to 99.8% by 120 min wet milling of celestite in 2 M Na2CO3 solution.
M-10: Effect of Strontium on Surface Oxide Structure of Liquid Al-12Si Alloy: Ugur Alev1; Gurer Zeren1; Derya Dispinar1; Cem Kahruman1; 1Istanbul University
Bifilms are known to be one of the most important defects in casting of aluminium alloys which are surface entrained oxides, mostly incorporated into the melt by turbulence. Therefore, it is important that the characteristics of oxides that may form on the surface of aluminum alloys need to be determined. The main purpose of the study was to reveal more clearly characterization of oxide structure of Sr-modified Al-12Si Alloy. The alloy was modified by 100, 200 and 300 ppm Sr. Afterwards experiments were carried out at 700, 750 and 800 °C for 12, 24, 36 and 48 hours. The samples surface oxide structure were investigated by optic microscopy, SEM, XRD and also XPS technique.
M-11: Enhancement of Strength and Formability for Super-light Mg-Li Alloys: Hyeon-Taek Son1; Yong-Ho Kim1; Hyo-Sang Yoo1; 1Korea Institute of Industrial Technology
Li addition in Mg alloys transforms the crystal structure from HCP to BCC with more slip systems. Moreover, when Li content is between 5.7 and 11wt%, Mg-Li alloys have two-phase structure that consists of the α-Mg and β-Li phases at room temperature. The addition of Li to Mg alloys with greater than that about 11wt% cause the crystal structure to transform to single BCC β phase. Therefore, Li addition in Mg alloys can significantly improve the formability.However, Mg-Li alloys have low strength and poor corrosion resistance, which is not beneficial for their application. In order to improve mechanical property, various alloying element have been added to Mg-Li alloy systems. In the present study, Mg-Li based alloys were prepared by the casting, hot extrusion and rolling process. The effects of trace element and Li contnents on strength and formability of the Mg-11Li based alloys were investigated.
M-12: Evaluation of Anodized Aluminum for Potential Use as an Interposer for the Test Socket Industry: Boon-Chai Ng1; Will Allen1; Dominique Tan-Ng2; 1Andrews University; 2Andrews Academy
Interposers are used to position pins or helical springs to analyze the connectivity of printed circuit boards. These interposers are made of plastics, but the dimensional accuracy of these polymers are hampered by the increase in temperature during usage. A new material that is easy to manufacture, a good insulator, and unhindered by the increase in temperature is desirable. Anodized aluminum would fulfill this criterion. 6061 aluminum alloy were anodized and the samples were subjected to thermal cycles to simulate actual working conditions. These samples were then examined under a scanning electron microscope for possible cracks that might have resulted due to the differences in thermal expansion rates of the oxide and the aluminum matrix. Initial results showed no surface cracks suggesting that anodized aluminum would be a good candidate to spearhead the next generation of interposers with better control of dimensional accuracy in test sockets.
M-13: Fabrication of Cu-Be Alloy Matrix CNT Composite and Enhancement of Materials Properties: Kwang-jin Lee1; Yeong-seok Kim2; Sang-don Mun2; 1Korea Institute of Industrial Technology; 2Chonbuk National University
This study was performed to fabricate of Cu-Be alloy matrix CNT(Carbon Nano Tube) composite by using a laser aided process. It was also conducted to investigate microstructural evolution during the process and to evaluate the physical and mechanical properties of the composite. At first, micro-holes are drilled on the surface of the Cu-Be alloy plate and CNT reinforcements are filled in each micro-hole. A precisely controlled laser beam is irradiated at the center of micro-holes clusters. Consequently, Cu-Be alloy matrix CNT composite wells are formed on the surficial region of the Cu-Be alloy plate. Microstructure was investigated by OM, FE-SEM, TEM techniques. Mechanical and physical properties were measured by several tests at room temperature. Materials properties of the composite were better than those of the Cu-Be alloy. It’s considered that the improvement of materials properties in the Cu-Be alloy matrix CNT composite was caused by homogeneous distribution of CNT particles.
M-14: Global Solar Radiation as an Alternative to Energy Production for Earth Climate System Using Common Meterological Data: Bukola Dawodu1; Hammed Ogundiran2; Isa Elegbede3; 1University Of Lagos; 2Fountain University; 3Brandenburg University of Technology
The quest to reduce environmental impacts of conventional energy resources and importantly meeting the growing energy demands of the global population, had motivated considerable research attention in a wide range of environmental application of renewable form of energy. In this study, the global solar radiation on horizontal surface in Osogbo, Nigeria using 1-year data (May 2014–June 2015) was analysed. Simple empirical correlations for evaluating the monthly average daily global solar radiation were developed. The Angstrom–Page correlation predicted the monthly average daily global solar radiation better than the other correlations developed in this study. The correlations presented in this study could be applied to locations with comparable weather conditions. Global solar radiation is of economic importance as a renewable energy alternative, recently global solar radiation has being studied due to its importance in providing energy for Earth’s climate system.
M-15: Graphite Supported Template Synthezed Intermetallic Co-Ni Nanoparticles for Biomedical Applications: Mehmet Burcin Piskin1; Ivania Markova2; Emre Karaduman3; Ivan Zahariev2; 1Yildiz Technical University ; 2University of Chemical Technology and Metallurgy-Sofia, Bulgaria; 3Yildiz Technical University
Co-Ni core/carbon-based shell nanoparticles are synthesized at room temperature by the help of a template technique using a carbon-containing support through a chemical borohydride reduction with 0.2M NaBH4 in a mixture of aqueous solutions of 0.1M CoCl2.6H2O and 0.1M NiCl2.6H2O at a different ratio Co:Ni (1:4, 1:1, 4:1). As a support is used fluorinated graphite (CF) in the presence of β-cyclodextrine (β-CDx). Scanning electron microscopy (SEM), Energy dispersitive spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transformation (FTIR) analyses are carried out to determine the structural properties of the prepared hybrid core/shell nanoparticles. These Co-Ni nanoparticle powders reveal a good magnetic behavior, which would be applicable for biomedical applications as diagnostic tools and smart treatment agents in cancer and other disеases. The obtained magnetic nanosized Co-Ni particles have no deleterious impact on biological tissue.
M-16: Hot Deformation Properties of 5xxx Aluminum Alloys for Automotive Applications: Paul Ebenberger1; Bodo Gerold2; Ramona Prillhofer2; Anna-Catharina Kaiß2; Peter Uggowitzer3; Stefan Pogatscher1; 1Montanuniversitaet Leoben; 2AMAG rolling GmbH; 3ETH Zürich
Aluminum alloys such as AA5083 are commonly used for hot sheet deformation techniques like superplastic forming or quick plastic forming in the automotive industry. Favorable properties at these high temperatures (e.g. high strain rate sensitivity and formability) are facing the problem of low deformation velocity in superplastic forming processes. In the past, a lot of effort has been made to improve the deformation rate behavior using e.g. copper addition or high content of manganese. The present investigation aims at an optimization of the processing parameters temperature and deformation rate for different AA5083 alloys with systematic changes in the chemical composition. The deformation behavior of the alloys was studied via tension tests and forming limit diagrams at various temperatures. The results are discussed within the framework of active deformation mechanisms and the effect of individual alloying elements on the microstructure.
M-17: Improvement of Corrosion Resistance of Low Carbon Steel by Ni-electrodeposition with Reduced Graphene Oxide: Jung-Woo Choi1; Gye-Won Kim1; Bongyoung Yoo1; Dong-Hyuk Shin1; 1Hanyang University
This study demonstrates how to improve the corrosion resistance of low carbon steel by Ni-electrodeposition with reduced graphene oxide (rGO). For this purpose, the electrodeposition processes were carried out in the Ni-based electrolytes with and without rGO and Na2SiO3 at a current density of 100 mA/cm2 using DC power supply. Based on the Raman shifts by Raman spectroscopy, the existence of rGO in the coating layer was identified qualitatively. The refined micro structure was observed on the coating layer with rGO, compared to that without rGO, whereas rGO was ineffective in the coating growth. The results of electrochemical corrosion analyses clearly exhibited that the corrosion resistance of the Ni-electrodeposited low carbon steel with rGO was superior to that without rGO and the bare low carbon steel.
M-18: Influence of Addition of Alumina Nanoparticles on Thermoelectric Properties of Bi0.4Sb1.6Te3 Fabricated by Mechanical Alloying and Vacuum Hot Pressing: Pee-Yew Lee1; 1National Taiwan Ocean University
In this study, γ-Al2O3 nanoparticles were dispersed in p-type Bi0.4Sb1.6Te3 through mechanical alloying to form γ-Al2O3/Bi0.4Sb1.6Te3 composite powders. The composite powders were consolidated using vacuum hot pressing to produce nano- and microstructured composites. Thermoelectric (TE) measurements indicated that adding an optimal amount of γ-Al2O3 nanoparticles improves the TE performance of the fabricated composites. High TE performances with figure of merit (ZT) values as high as 1.22 and 1.21 were achieved at 373 and 398 K for samples containing 1 and 3 wt % γ-Al2O3 nanoparticles, respectively. The achieved high ZT value may be attributable to the unique nano- and microstructures in which γ-Al2O3 nanoparticles are dispersed among the grain boundary or in the matrix grain, as revealed by high-resolution transmission electron microscopy. The dispersed γ-Al2O3 nanoparticles thus increase phonon scattering sites and reduce thermal conductivity.
M-19: Influence of Microstructure and Strain Hardening on Rheological and Fatigue Resistance of Cu-Ag Alloys Wires: Artur Kawecki1; Kinga Korzeń1; Eliza Sieja-Smaga1; Andrzej Nowak1; Tadeusz Knych1; Andrzej Mamala1; Beata Smyrak1; Małgorzata Zasadzińska1; 1AGH University of Science and Technology
The paper presents results of studies on Cu-Ag (1-15 wt.%) alloys continuous casting process and cold drawing of obtained casts which allowed to obtain very high mechanical (UTS=900-1600 MPa) and electrical (63-90 % in IACS scale) properties of wires. The paper also presents the results of rheological and fatigue resistance tests carried out on the wires in as-cast state and after various thermo-mechanical treatment processes. The optimum parameters of the thermo-mechanical treatment of the alloy were determined, enabling to obtain most preferable mechanical and electrical properties of wires. The influence of materials microstructure and their value of deformation on the changes in rheological and fatigue properties of wires was also determined. In addition, a microstructural analysis was carried out on casts and wires using SEM and TEM microscopy.
M-20: Role of ZnO Nanoparticle Reinforcing the Ductility of Al-Si Alloys: Sangjun Lee1; Donghyun Bae1; 1Yonsei University
Al-Si alloys are used in wide range of applications due to its low density, high strength and ductility. For enhancing the mechanical properties of Al-Si alloys, alloying elements such as Mg, Zn, and Cu are selected for strength and castability. However those of elements form eutectic phase with Al, so that it has low workability. For enhancing the workability of aluminum alloys, we tried to reinforce ductility at first. Therefore, we selected ceramic nanoparticle ZnO, adding in Al-Si alloy, as reinforcement to Al-2Si alloy matrix for enhancing the mechanical properties. Tensile test is performed to evaluate the mechanical properties and SEM observation is carried out to prove uniform dispersion of ceramic nanoparticle. As the result, uniformly dispersed 1vol.% ZnO nanoparticle reinforced Al-2Si alloy shows 25% ductility than that of unreinforced alloy.
M-21: Sigma-phase Formation in the Reaction Zone between Mo-41Re Alloy and SiC during Diffusion Bonding: Seung-Sik Jang1; Sun-Kyu Lee1; Godwin Kwame Ahiale1; Yong-Jun Oh1; 1Hanbat National University
The reliability of refractory metals−ceramic joints is of great interest because of their potential applicability in components operating at extremely high-temperature environments. The precipitation behavior of the detrimental σ-MoRe phase at the interface between SiC and Mo-41wt%Re alloy bonded at 1773 K was investigated. The reaction zone at the interface was studied using transmission electron microscopy (TEM) and electron probe microanalysis. Si atoms were diffused into the surface of Mo-Re alloy to form Mo silicides during bonding. The reaction reduced Re solubility in the region and facilitated backward diffusion of Re atoms, which resulted in a granular σ-MoRe phase at a depth of 10~20 μm from the alloy surface. The granular σ-MoRe phase triggered cellular precipitation of the σ-phase that extensively grew into the alloy (α to α’+σ). The detailed reaction mechanism would be elucidated with TEM microanalysis.
M-22: Study on a Bipolar Plate Corrosion Properties for an STS316 and STS430 Specimen's on the PEMFC Environment by the Surface Treatment through Low-temperature TiAlCrN PVD Process: Min Seok Moon1; Myeong Han Yoo1; Joon Hyuk Song1; Je Ha Oh1; Jong Il Rho1; Shin Jae Kang2; Kee Do Woo2; Sung Mo Yang2; Young Choi3; 1Korea Institute of Carbon Convergence Technology; 2Chonbuk National University; 3KITECH
PEMFC system is adopting on the automotive industries. As we know that automotive components request for their weight reducing. The normal PEMFC’s bipolar plate weight ratio is approximately 40% on the PEMFC system. Bipolar plates are an essential element of PEMFC and other fuel cells. Therefore, the bipolar plate weight reducing is a vital issue on the Fuel Cell manufacturer and user. In this investigation is the focus with bipolar plate’s weight reducing and total fabrication cost of a fuel-cell stack. In this study that tries to the durability increasing during the operating condition through metallic specimen’s surface modification by low-temperature PVD process. This study measured the electrochemical property, mechanical property, and single cell test for the TiAlCrN coated on all samples.
M-23: Study on the Behavior of Ultrafine-grained, Precipitation Strengthened Steels at High Strain Rates: Janusz Majta1; Remigiusz Bloniarz1; 1AGH University of Science and Technology
The real challenge for computer modeling is a properly built rheological model of ultrafine-grained (UFG) materials under dynamic loading conditions. The fundamental mechanisms at micro, meso-meter level and the continuum are discussed in this work across a range of strain rates. The main objective of this study was two-fold: i) improve the knowledge of the strengthening mechanisms of these materials at high strains, ii) based on this knowledge, propose a microstructurally aware constitutive description. The role of solute segregation at grain boundaries, dislocation substructure as well as precipitation in the investigated UFG structures was assessed. The dynamic behavior of two different materials: microalloyed ferrite (b.c.c.) and microalloyed austenite (f.c.c.) was studied in: SHPB, Taylor and Drop-Weight tests. Experimental analyses revealed that the investigated steels are strain rate sensitive, in fact, under high strain-rate conditions UFG microalloyed ferrite represents significantly higher sensitivity than microaloyed austenite.
M-24: Study of the Effects of High Temperature Processing on Microstructure and Texture Evolution in Ti Alloys based on Reconstruction of Beta Phase Using EBSD Data: Maciej Szymula1; Mateusz Sternalski1; Łukasz Madej1; Brad Wynne2; Krzysztof Muszka1; 1AGH Univeristy of Science and Technology; 2The University of Sheffield
Possibilities of direct observation of microstructure and texture in Ti alloys during high temperature processing are still limited due to a lack of suitable experimental techniques. The main reason is phase transformation that takes place in these materials and changes the phase from beta to alpha (upon cooling). Due to that fact, a detailed study of the effects of thermomechanical processing above beta transus temperature on microstructure evolution is very limited. In the present work, reconstruction algorithm that, using Burger's relationship, enables to reconstruct beta micrsostructure and texture based on EBSD data recorded at ambient temperature. Possibilites of beta phase reconstructions will be presented using two different titanium alloys (Timetal 834 and Timetal 6-4). Additionally, conclusions regarding effects of processing conditions above beta transus and in the intercritical conditions on reconstruction possibilities will be drawn.
M-25: Structural Characterization of NaF–AlF3 Melts Used in Aluminum Refining by High- temperature Raman Spectroscopy: Xianwei Hu1; Jingjing Liu1; Gaowei Li1; Zhongning Shi1; Bingliang Gao1; Wenju Tao1; Jiangyu Yu1; Zhaowen Wang1; 1Northeastern University
Electrolytic refining using the three-layer process is the primary method for producing refined aluminum, and NaF–AlF3 melt is the basic electrolyte in this process. In this study, Raman spectra of NaF–AlF3 melts with the composition used in the practical aluminum refining process are recorded and the structure of the melts is investigated by combining quantum chemical calculation. The results have indicated the presence of AlF4- tetrahedron and entities containing two or more AlF4- tetrahedron connected by “bridge fluoride” in the melts. Moreover, the structural parameters of related Al–F complex are determined.
M-26: Synthesis and Characterization of Al–B4C Powders by Mechanical Alloying: Hao Guo1; ZhongWu Zhang1; Yu Zhao1; Songsong Xu1; Junpeng Li1; Jing Zhang1; 1College of Materials Science and Chemical Engineering, Harbin Engineering University
Boron carbide reinforced aluminum matrix composites are widely used as neutron absorption materials. Here we report that mechanical alloying has been successfully employed to synthesize metal matrix composite powders with a nanograin Al as the matrix and B4C as the reinforcement. The effects of milling time on the size distribution, morphology of the milled powders as well as the grain size of the matrix alloy are investigated. The XRD results confirmed that the grain size of aluminum reached to 19nm and lattice distortion increased much after 130h milling of powder mixture. The DSC results showed that the melting point of Al decreased several degrees after 130h milling of powder mixture. Some physical phenomena, such as phase transformation during mechanical alloying and their effects on the mechanical properties of hot pressured specimens are also discussed.
M-27: The Effect of Temperature on Fracture and Fatigue in the High-entropy Alloy CrMnFeCoNi: Keli Thurston1; Bernd Gludovatz2; Guillame Laplanche3; Anton Hohenwarter4; Robert Ritchie2; 1UC Berkeley; 2Lawrence Berkeley National Laboratory; 3Ruhr University; 4Montanuniversität Leoben
High and medium-entropy alloys have garnered increasing attention as they not only represent a new approach to alloy design but also member alloy compositions have shown interesting combinations of mechanical properties such as increasing ductility and strength as temperatures are lowered into the cryogenic regime. In this work, we explore the fracture and fatigue behavior of the ‘Cantor alloy’ CrMnCoNiFe and its ternary subsidiary CrCoNi at both ambient and cryogenic conditions. Compact tension specimens were used for fracture toughness testing and disc-shaped compact tension specimens equipped with a back-face strain compliance gauge for crack length monitoring were tested under sinusoidal loading high-cycle fatigue. Examination of the fracture surfaces and the microstructure in the vicinity of the extended crack were conducted using EBSD and SEM imaging techniques. Decreasing temperature was found to increase the fracture toughness of both alloys and shift the fatigue threshold to higher ΔKs.
M-28: Thermomechanical Fatigue Behavior of Heat-resistant Cast Austenitic Stainless Steel for Automobile Turbocharger Housing: Godwin Kwame Ahiale1; Seungmun Jung2; Sunghak Lee2; Yong-Jun Oh1; 1Hanbat National University; 2Pohang University of Science and Technology
The fatigue life and microstructural evolution during thermomechanical fatigue (TMF) in heat-resistant cast austenitic stainless steel were evaluated. The TMF test was conducted at a minimum temperature of 200 °C and varied maximum temperatures of 800 to 950 °C under out-of-phase condition. Furthermore, an isothermal low-cycle fatigue (LCF) test was conducted at 900 °C. Increase in the maximum cycling temperature decreased the TMF life by coarsening the carbide phases in the microstructure, which acted as a defect by creating voids for crack propagation. The LCF specimens tested at 900 °C showed lower fatigue life than the TMF tested at Tmax = 900 °C. The stress response under TMF was marked by a significant hardening for specimens with Tmax = 800 °C, followed by those with Tmax = 900 °C and Tmax = 950 °C, in contrast to continuous softening in case of the LCF specimens.
M-29: Transitioning Ideas to Reality: Melding Casting and Additive Manufacturing to Advance Engineering Education: Matthew Willard1; James McGuffin-Cawley1; 1Case Western Reserve University
Materials science and engineering is a discipline that easily lends itself to a learning-by-doing methodology. However, in practice this can be challenging due to to complexities of working with real materials, especially under the constraints of safety concerns, limited resources, and restricted duration of projects. This work will describe the results of a materials discovery laboratory designed for first year engineering students with interest in materials. During the half-semester project, students made a miniature Academy Award in their own likeness, using additive manufacturing of polymer (ABS), elastomer polymers (silicone), and conventional casting (Sn-based pewter). This presentation will describe the process used and the outcomes of the project.
M-30: Ultrasonic Vibration Assisted Laser Surface Engineering of Aluminum Alloys: Sourabh Biswas1; Seyyed Habib Alavi1; Sandip Harimkar1; 1Oklahoma State University
Ultrasonic vibration assisted laser surface melting and laser composite surfacing were performed in this investigation. The laser melting experiments were primarily focused towards analysis of the influence of USV in the microstructure and texture evolution of the substrate. The aforementioned samples were subsequently examined using SEM, XRD, microhardness, potentiostatic and potentiodynamic characterization studies to establish their microstructural, mechanical and electrochemical properties. They exhibited confirmatory evidence that the USV was highly efficient in generating a refined microstructure. Also, while the laser processed samples demonstrated significant increase in open-circuit potential (η), the refined grains were not effective in increasing the hardness of the laser processed layer. Additionally, laser composite surfacing under the influence of USV of aluminum alloys with SiC was also successfully performed and its tribological properties were recorded. It was clearly observed that the USV increased the coating thickness and simultaneously decreased the wear rate.
M-31: Variation of Thermal Diffusivity of Cu-RGO Composites by SPS Process: Hyo-Soo Lee1; Yeo-Reum Lee1; Sangwoo Kim1; 1KITECH
It was investigated that Cu-RGO(Reduced Graphene Oxide) composites were varied by increasing volume fraction of RGO ranged from 0 to 7 vol.%. The micro-scaled Cu powders and nano-scaled RGO flakes were mixed by ball mill process at 150rpm for 4hours. The Cu-0~7vol.%RGO composite powders were formed. The composite powders were sintered by SPS process at 700℃ for 10mins under 100MPa, and the sintered Cu-RGO composites were characterized by X-ray diffraction, SEM, TEM, raman spectroscopy, and laser flash analyzer. It was observed that the RGO flakes were extensively stuck to the surface of Cu powders in Cu-RGO composite powders, which was considered as an effective path of thermal dissipation in the sintered Cu-RGO composites. It was shown in this study that the thermal diffusivity of Cu-0~7%vol.RGO composite were 90~100m2/s which was similar to that of pure copper.
M-32: Correlation between Microstructure Evolution and Mechanical Properties of Al 6061 Alloy Fabricated by Differential Speed Rolling after Cryogenic Treatment: Haewoong Yang1; Yong Hwan Lee1; Danasesha Paradinda Putra1; Young Gun Ko1; 1Yeungnam university
This paper reports the correlation between microstructure evolution and mechanical properties of Al 6061 alloy fabricated by cryogenic differential speed rolling (CDSR). The combination of cryogenic treatment with differential speed rolling (DSR) effectively increased mechanical properties without an appreciable decrease in ductility through the ultrafine grained the Al 6061 alloy. For this purpose, the Al 6061 alloy has been subjected to DSR process at a cryogenic temperature of 90 K and the results were compared with that processed via DSR. Microstructural analyses using optical image (OM) and electron backscattered diffraction (EBSD) measurements showed that the samples with CDSR resulted in ultra-fine grain with improved uniformity as compared to that processed with DSR. In addition, uniformity of vickers microhardness for the samples via CDSR was higher than that via DSR.
M-33: Corrosion Characteristics of Ti-free B Grain Refined A360: Eda Ergun Songul1; Cemre Bas1; Derya Dispinar1; Gokhan Orhan1; 1Istanbul University
A360 contains around 9-10wt % Si which is a near eutectic alloy. Although this alloy suffers from castability, however the toughness is higher than 12wt% Si eutectic composition. It is a preferred choice of material particularly for high pressure die casting application. Due to fading effect of Ti, Al-3B is used for grain refinement of aluminium alloys. In literature, mechanical properties of this alloy can be found. However, there are not much works on the corrosion behaviour of this alloy. Therefore, in this work, characterisation of HPDC A360 alloy that contained various amounts of B have been investigated. Microstructural analysis was carried out and Tafel curves were plotted. Weibull statistical analysis was used to determine the reliability of the test results.
M-34: Correlation between Corrosion Resistance and Microstructure of Al-12Si Eutectic Alloy: Cemre Bas1; Yurdanur Temel1; Eda Ergun Songul1; Derya Dispinar1; Gokhan Orhan1; 1Istanbul University
Eutectic Al-Si alloys exhibit good castability and high wear resistance. However, this alloy can be brittle. In order to improve mechanical properties, silicon shape and size is altered by the addition of Sr into the alloy. Main function of Sr is to hinder Si growth and thus fibrous and finely distributed microstructure is obtained. In this work, the characterisation of the corrosion behaviour of A413 (Al-12Si) alloy was evaluated by using electrochemical impedance spectroscopy. Tafel curves were also plotted. To obtain different microstructures, the alloy was cast into sand and die moulds with and without Sr modification to produce cylindrical bars. Overall, the corrosion behaviour of A413 was evaluated.