2020 Technical Division Student Poster Contest: MPMD 2020 Technical Division Graduate Student Poster Contest
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
Monday 5:30 PM
February 24, 2020
Room: Sails Pavilion
Location: San Diego Convention Ctr
SPG-36: An Investigation on Internal Oxidation of FeCrAlY Alloys in Selective Laser Melting: Saereh Mirzababaei1; Milad Ghayoor1; Somayeh Pasebani1; 1Oregon State University
Oxide dispersion strengthened (ODS) FeCrAl alloys are promising candidates for harsh environments due to their high strength and oxidation resistance at elevated temperatures. Conventionally, mechanical alloying of FeCrAl with yttria nanoparticle followed by hot consolidation was used to manufacture ODS FeCrAl alloy. This work aimed to adopt additive manufacturing, in particular, selective laser melting (SLM) to investigate the feasibility of manufacturing ODS FeCrAl alloys via internal oxidation. Such that, FeCrAlY powder was used in presence of the residual oxygen inside the SLM chamber with no additional need for mechanical alloying with yttria nanoparticles. Gas-atomized Fe–24Cr–8Al–0.5Y (wt.%) powder was procured from Orlikon Metco (D50=33μm) and characterized for morphology, powder size, and size distribution. Cylindrical samples were built via SLM using Coherent/OR Creator. The microstructure of fabricated parts was investigated using optical and scanning electron microscopy. Mechanical properties of parts were measured and compared with conventionally manufactured FeCrAly parts.
SPG-37: Automatically Quantifying Phase Information from HRTEM for Additively Manufactured Materials: Sen Liu1; Behnam Amin-Ahmadi1; Branden Kappes1; Aaron Stebner1; Xiaoli Zhang1; 1Colorado School of Mines
Additive manufactured (AM) metals have a unique initial microstructure that requires custom heat treatments. AM Inconel 718 precipitation strengthening relies on the coprecipitation of γ' and γ'' phases. High resolution transmission electron microscopy (HRTEM) has been used to track precipitation growth behavior during post processing. Identifying nanoprecipitates evolution during heat treatments requires hundreds of images and thousands of precipitates. Computer vision (CV) coupled with machine learning (ML) segmentation automatically extract and quantify phase information with angstrom-scale resolution, allowing for quantitative correlation between nanostructure formation and processing conditions. We introduce a sliding Fast Fourier Transform (FFT) to automatically segment unique phases from HRTEM. The image processing used is largely insensitive to image variations. An unsupervised ML was used to automatically group similar phases, which is unique to composition and orientation of constituent phases. This study shows the promise of ML for enabling high-throughput materials characterization to accelerate AM materials development.
Cancelled
SPG-38: Characterization of the Corrosion of Nanostructured 17-4 PH Stainless Steel by Surface Mechanical Attrition Treatment (SMAT): Temitope Olugbade1; Jian Lu1; 1City University of Hong Kong
The corrosion properties of nanostructured 17-4PH stainless steel facilitated by a surface mechanical attrition treatment (SMAT) process were studied using electrochemical measurements in 0.6 M NaCl aqueous solution. The microstructure of the surface layer was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results demonstrated the formation of a nanostructured surface layer on the surface of the material. By the combination of SMAT and low-temperature annealing processes, the potentiodynamic polarization measurements and X-ray photoelectron spectroscopy (XPS) spectra demonstrated an improvement in the corrosion resistance of 17-4PH stainless steel with a reduced corrosion current density of 0.241 mA/cm2 and a higher chromium content. The improved corrosion resistance may be attributed to the formation of nucleation sites through which chromium may freely move from the matrix to the upper surface and thereby form a protective oxide layer on the surface of the material.
SPG-39: Effect of Microtopography on Guided Cell Migration on a Graded Micropillar Substrate: Srikumar Krishnamoorthy1; Changxue Xu1; 1Texas Tech University
Cell migration is facilitated by the interaction of cells with their local microenvironment including geometry, stiffness, and chemical gradients. Construction of an interface to achieve guided cell migration is of great significance for studying cell behaviors. In this presentation, a dynamic mask photolithography technique has been implemented to fabricate a graded micropillar substrate. Three different types of cells are seeded on the fabricated substrate after surface treatment. Successful guided cell migration has been demonstrated on the graded micropillar substrate. The effects of the micropillar gradient, diameter, and height on the migration speed and cellular morphology have been systematically investigated. Moreover, endothelial cells, fibroblasts, and breast cancer cells have been utilized to compare different migration behaviors on the graded micropillar substrate.
SPG-40: Elucidation of Solidification Kinetics in Laser Spot-fusion Processing of Ti-6Al-4V Alloy Using In-situ X-ray Synchrotron Radiography: Rakesh Kamath1; Logan White1; Ryan Heldt1; Yuan Li1; Tao Sun2; Sudarsanam Babu3; Hahn Choo4; 1University of Tennessee Knoxville; 2Argonne National Laboratory; 3Oak Ridge National Laboratory; 4University of Tennessee, Knoxville
A thorough understanding of relationships between process parameters and final microstructure is of utmost importance to facilitate the utilization of fusion-based metal additive manufacturing (AM) technologies to their maximum. In this study, a laser-AM simulator (commissioned at beamline 32-ID-B, APS) was employed to examine the effects of spot melt strategies on liquid-solid and solid-solid transformations in Ti-6Al-4V alloy with varying parameters such as laser power, spot dwell time and intervals between successive spot melts. The aforementioned laser melting “events”, produced using the laser-AM simulator, were recorded using in-situ synchrotron x-ray radiography and were subsequently analyzed to obtain the liquid-solid interface velocity (V). Post-mortem EBSD characterization was used to indirectly estimate the thermal gradient (G) across the liquid-solid interface. In addition to throwing more light on liquid-solid transformations (using G & V), the effect on solid-solid transformations in the precursor melt due to the subsequent melt were studied using post-mortem EBSD.
SPG- 41: Evaluation of Two Novel Techniques to Characterize the Bond Strengths of Cold Sprayed Single Particle Impacts: Matthew Gleason1; 1Worcester Polytechnic Institute
In order to better understand the cold spray bonding process, it is necessary to experimentally assess the bond strengths of individual particle impacts. While there exist several techniques for this purpose in the literature, each possess limitations that restrict their usefulness. Some are too time intensive to gather enough data for statistical investigations, while others sacrifice measurement accuracy. We have previously proposed two novel techniques that exceed these limitations, each allowing for high throughput characterization while still maintaining high accuracy. One is a novel method of sample preparation that results in a sample geometry that is easy to test, while the other is a type of crack propagation test. In this work preliminary experiments are performed with both methods to evaluate and compare their effectiveness.
SPG-42: Exploring the Structure-processing Relationship: Direct Ink Writing of Functionally Graded Carbides: Joshua Pelz1; Nicholas Ku2; Samuel Figueroa1; Marc Meyers1; Lionel Vargas Gonzalez2; 1University of California, San Diego; 2US Army Research Laboratory
Direct ink writing is explored as a processing technique to research and develop functionally graded carbide materials with improved mechanical properties for structural applications. This study identifies several key processing parameters that may be adjusted to tailor micro- and mesostructural features. The presented work utilizes a custom designed direct ink writing system with multi-material and in-line mixing capabilities for printing inks consisting of high solids-loaded, colloidal ceramic particulate slurries. The custom system has two modules, the print head and the feed system, and interfaces with a commercially-available, desktop 3D printer. The feed system inputs ink to the print head, which uses an auger to mix and extrude material from a single nozzle. Auger parameters such as length, thread pitch, and channel depth were adjusted to tune the shearing action in the print head. Effects on extrusion rate and mixedness were quantified through characterization of printed filaments and specimen cross-sections.
Cancelled
SPG-43: Helium Bubble Induced Surface Blistering Study of Grain Boundary Engineered Tungsten under Helium Implantation: Tianyao Wang1; 1Texas A&M University
Tungsten is one identified candidate material for fusion applications. Swelling and blistering of tungsten by helium ion irradiation has been well studied. However, the effects of grain boundaries in boundary-engineered W are not thoroughly investigated, particularly the correlations of boundary configuration and morphology to boundary defect sink strength. In this study, we reported defect evolution in He implanted W, which are prepared by equal channel angular extrusion (ECAE) processing. 100 keV He ions were implanted at temperatures from 600K to 1000K, at a ion fluence up to 2X1018/cm2. The study shows that grain boundary can act as not only diffusion sinks but also fast diffusion paths to remove He from the bulk. Hence, swelling and blistering resistance can be significantly enhanced for boundaries which have a texture favoring quick He release.
SPG-44: Modeling and Predicting Longitudinal Defect Mechanisms in Steel Continuous Casting: Matthew Zappulla1; Brian Thomas1; 1Colorado School of Mines
Harsh environments in the continuous casting of steel prevent most types of in-situ measurement and observation techniques. Slight local disruptions to the desired uniform thermal and mechanical conditions within the mold often lead to solidification defects. These defects are often only discovered in the process far down-stream from the origin point within the mold. A new methodology has been developed to elucidate the formation mechanism of these defects within the mold region using only the final shape of the defect on the cast slab. Using a thermal-mechanical finite element model conditions within the mold are simulated and loading conditions that mimic caster behavior are imposed. The general shape of the defect is found to vary with disruption severity and loading type, creating distinctly different types of longitudinal defects; additionally the presence of different sizes and types of cracks also dramatically affects the development of the defect.
SPG-45: Optimization of Heat-treatment on Recycled Stainless Steel Powder for Cold Spray Applications: Christopher Massar1; Kyle Tsaknopoulos1; Bryer Sousa1; Danielle Cote1; 1Worcester Polytechnic Institute
As one of the most fundamental structural materials, accounting for 95% of the metal tonnage produced in the US, the recyclability of steel is a necessity. This investigation explores the optimization of mechanical properties through the heat treatment of stainless-steel powder produced through scrap steel atomized using Molyworks’ Mobile Foundry for Cold Spray (CS) applications. This AM feedstock is characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), nanoindentation (NI), and powder x-ray diffraction (PXRD). Heat treatment considerations are based on thermokinetic modeling using Thermocalc and Dictra software.
SPG-46: Spark Plasma Sintering of Mechanically Alloyed In-situ Ni-Ti-C Nanocomposites: Amit Patil1; 1Cleveland State University
Ni-Ti-C metal matrix composites (MMC) with in situ formed, homogeneously distributed titanium carbide (TiC), as well as graphite reinforcement in nickel metal matrix, were synthesized using Mechanical Alloying (MA) followed by Spark Plasma Sintering (SPS). MA has gained special attention as a powerful non-equilibrium process for the fabrication of nanocrystalline and composite materials, whereas spark plasma sintering (SPS) is a unique technique for processing dense and near net shape bulk MMCs with homogenous microstructures. These composites consist of an in situ formed and homogeneously distributed nanoscopic TiC and graphite precipitates reinforcing the nickel matrix. Additionally, by tailoring the Ti/C ratio in these composites, an additional graphitic phase can also be engineered into the microstructure. All in situ Ni-Ti-C composites exhibited excellent microhardness as well as tribological properties compared to pure nickel primarily due to presence of homogeneously distributed TiC and C precipitates within the nickel matrix.
SPG-47:The Effect of TiC Content and SPS Processing Parameters on Ni-TiC Composites: Ganesh Walunj1; Anthony Bearden1; 1Cleveland State University
The influence of variations in the TiC content employed during spark plasma sintering (SPS) of nickel-titanium carbide composites on its microstructure and mechanical properties has been investigated systematically. Mechanical alloying has gained special attention as a powerful non-equilibrium process for fabricating amorphous and nanocrystalline materials, whereas spark plasma sintering (SPS) is a unique technique for processing dense and near net shape bulk alloys with homogenous microstructure. Mechanical alloying was performed using planetary high energy ball mill with 400 rpm and ball to powder ratio 15:1 for 24 hours. Bulk Ni-TiC composites (with TiC content varying from 5 to 50 wt%) were fabricated via mechanical alloying followed by SPS at 65 MPa pressure and 900-12000C temperature. There is an increase in microhardness, as well as TiC peak intensity, which has been observed with increasing TiC content. These Ni-TiC composites exhibit excellent microhardness and tribological properties as compared to pure nickel.
SPG-49: Thermal Stability of Yttrium Oxide Nanoparticles in 304 ODS Alloy Additively Manufactured via Selective Laser Melting: Milad Ghayoor1; Kijoon Lee1; Yujuan He1; Chih-Hung Chang1; Brian K. Paul1; Somayeh Pasebani1; 1Oregon State University
Thermal stability of added yttrium oxide (Y2O3) to a 304L austenitic stainless steel matrix manufactured via selective laser melting (SLM) is investigated. Sandvik 304L SS powder and 0.5 wt.% of yttria nanoparticles were used as feedstocks in an OR Creator SLM machine. The laser power of 140W and scanning speed of 300 mm/s was used in a nitrogen atmosphere. The density of 99% and hardness of 350 HV were achieved in 304L ODS alloy. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed a homogenous distribution of Y-Si-O nanoparticles in the SLM 304L ODS alloy. At 800 °C, the yield stress of 151 MPa and ultimate tensile strength of 153 MPa were obtained; substantially higher than SLM 304L. Printed samples were kept at 1200°C for 100 hours in argon atmosphere. Microstructure and mechanical properties of 304L and 304L ODS are compared before and after thermal stability experiment.
SPG-51: Understanding Thermal Signatures using Infrared Monitoring of Laser Powder Bed Fusion (L-PBF): Sujana Chandrasekar1; Jamie Coble1; Amy Godfrey1; Serena Beauchamp1; Caitlin Hensley1; Travis Mcfalls2; Fred List3; Keith Carver3; Ryan Dehoff3; Vincent Paquit3; Sudarsanam Babu1; 1University of Tennessee, Knoxville; 2BWX Technologies; 3Oak Ridge National Laboratory
Additive Manufacturing (AM) represents a novel way of part production that has potential applications in niche fields like aerospace, nuclear and medical parts. One of the key challenges in metal AM is understanding different thermal cycles that occur in a part and consequent effects. Thermal cycling at each region of a part depends on part geometry, scan strategy, scan parameters and defects. Different thermal cycles can lead to different microstructures and change in properties. Our work demonstrates that change in thermal processing can be detected by analyzing in situ infrared videos of the build process as a time series and using similarity search algorithms. Changes corresponding to change in geometry and scan strategy have been detected. Further, different microstructures arising due to these changes have been observed and will be rationalized. The ability to scale pixelwise infrared video analysis to multiple layers will be presented.