December 2019 - Msepostdoc-list

Seminar Notice for Teal Dowd's Preliminary Exam. Seminar, Tuesday, December 17, at 12:30, in IMI 127. "Selective Laser Sintering: Coalescence Phenomena and the Effects of Process Parameters on Part Performance"
by Son, Rosemary E 11 Dec '19

11 Dec '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Selective Laser Sintering: Coalescence Phenomena and the Effects of Process Parameters on Part Performance" By Teal F. Dowd Purdue MSE Preliminary Exam Advisor: Professor Jan-Anders Mansson ABSTRACT Selective Laser Sintering (SLS) is a free-form three dimensional additive manufacturing process, capable of producing functional graded parts. The fundamental driving force for polymer SLS is coalescence of powder particles through reduction in Gibbs free energy once sufficient laser energy has been provided. The powder particles combine and densify through diffusion until a mostly dense part is created. Coalescence rate and quality are increased through smaller particles with high packing efficiency (optimized through binary size distributions), and using polymers with high mobility (low molecular weight and low viscosity). Part strength is highly dependent on correct build parameters. Research suggests that increased energy density (a function of laser power, scan spacing, and scan speed) is highly correlated with increased part modulus, density, and elongation at break, with the ceiling at the point of material degradation. Other major build considerations are build orientation, powder refresh rate, preheat temperature, base polymer crystallinity, and particle chemistry. Date: Tuesday, December 17, 2019 Time: 12:30 P.M. Place: IMI 127

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Seminar Notice for Amelia Leenig's Preliminary Exam. Seminar: Friday, Dec. 20, at 10:30 a.m., in ARMS 1103
by Son, Rosemary E 11 Dec '19

11 Dec '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Material Effects on the Performance of Athletic Cleated Shoe Stubs" By Amelia G. X. Leenig Purdue MSE Preliminary Exam Advisor: Professor Weinong Chen ABSTRACT Athletic cleated shoes are used in a wide variety of sports such as soccer, ultimate frisbee, lacrosse, football, baseball, etc. Most of the injuries in these sports occur without multiple player contact. Instead, translational and rotational friction interactions between shoe soles, feet, and playing surfaces can cause injuries to athletes. Cleat stub components play a large role in determining traction and friction characteristics of athletic cleated shoes. Therefore, it is important to understand how cleat stubs affect athletes' performance and how the material and physical properties change with increased use and aging. Cleat stubs are generally made of a polyether based thermoplastic polyurethanes (TPU). Degradation of TPU material properties occurs when exposed to UV-rays or elevated air temperatures for extended time periods. Surface characteristics are primarily affected when a TPU is experiencing fatigue or creep while aged in an oxidative solution. Determination of cleat stub performance can be characterized by the cyclic loading hysteresis loop response of TPUs. Cyclic loading behavior of TPUs indicates that the loading behavior is dependent on the strain rate induced on the material. Studies analyzed in this review provide some insight to how cleat stub materials will perform with increased use and environmental aging. Date: Friday, December 20, 2019 Time: 9:00 A.M. Place: ARMS 1103

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Found Keys in ARMS 2300
by Ku Blanco, Aury Y 11 Dec '19

11 Dec '19

Hi all, A set of keys was found in the commons area and returned to me at reception. Please let me know/stop by if these are yours 😊 Thank you, Aury Ku Administrative Assistant Purdue University School of Materials Engineering Neil Armstrong Hall of Engineering 765/494-4100 akublanc(a)purdue.edu<mailto:staceyl@purdue.edu> [https://www.purdue.edu/brand/images/Purdue_University-150_Years_of_Giant_Le…]

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Jimmy John's in Kitchen
by Ku Blanco, Aury Y 10 Dec '19

10 Dec '19

Hi all, Your assistance is required! There are a handful of Jimmy John’s sandwiches/chips up for grabs in the kitchen 😊 Please help yourselves to these. Thanks, Aury Ku Administrative Assistant Purdue University School of Materials Engineering Neil Armstrong Hall of Engineering 765/494-4100 akublanc(a)purdue.edu<mailto:staceyl@purdue.edu> [https://www.purdue.edu/brand/images/Purdue_University-150_Years_of_Giant_Le…]

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Seminar Notice for Joseph Anderson's Preliminary Exam. Friday, Dec. 13, at 9:30 a.m., in ARMS 1021 "The Statistical Mechanics of Interacting Particles (With Applications in Dislocation Dynamics)”
by Son, Rosemary E 09 Dec '19

09 Dec '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR “The Statistical Mechanics of Interacting Particles (With Applications in Dislocation Dynamics)” By Joseph P. Anderson Purdue MSE Preliminary Exam Advisor: Professor Anter A. El-Azab ABSTRACT The dynamics of smooth density fields of discrete entities (e.g. electrons, fluid particles, dislocations) depend strongly on the short-range order of the underlying discrete entities considered. Statistical mechanics presents a means of determining this short-range order from the interaction potential. However, the means by which that is accomplished is not straightforward. In this presentation we will discuss the extension of statistical mechanics to interacting systems, and how this short-range order emerges in the equilibrium of such a system. This involves such topics as the Born-Bogoliubov-Green-Kirkwood-Yvon (BBGKY) hierarchy of densities (of which the radial distribution function [cid:image002.png@01D5AEAE.52D8F370] is a special case) and closure approximations to this hierarchy. By means of a geometric interpretation of the ergodic theorem, we will examine under which regimes of interaction strength these methods may be applied, as well as the two-temperature models used to work around issues of ergodicity. Finally, we will discuss how dynamic theories which hold well beyond equilibrium may be formed from a description of short-range structures. This discussion will include projection operator approaches, as well as a formalism known as the General Equation for Non-Equilibrium Reversible Irreversible Coupling (GENERIC). Throughout, we will discuss the application of these ideas to the topic of dislocation dynamics, as well as the issues which arise in that application. . Date: Wednesday, December 13, 2019 Time: 8:00 A.M. Place: ARMS 1021

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Seminar Notice for Saswat Mishra. Dec. 12, at 9:00 a.m., in ARMS 1103 "First-principles Approach to Model Point Defects in Materials and Predict their Corresponding Thermodynamic Transition States"
by Son, Rosemary E 09 Dec '19

09 Dec '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "First-principles Approach to Model Point Defects in Materials and Predict their Corresponding Thermodynamic Transition States" By Saswat Mishra Purdue MSE Preliminary Exam Advisor: Professor Alejandro Strachan ABSTRACT Defects are ubiquitous in materials and affect their physical, structural, chemical, and electrical properties. It is difficult to detect electronic states far from the band edge experimentally, and hence a few defect levels are challenging to characterize. First-principles study of defects can provide crucial insight into the position of these electronic trap states by complimenting experimentally observed states. However, the potential of a charged system under periodic boundary conditions diverges. Various techniques have been suggested to model charged defects using density functional theory (DFT), which use approximations to determine the energy. These approximations introduce spurious effects and taint the result, which can be corrected using various schemes. This work aims to compare two such correction schemes applied to a simple Silicon vacancy system and comment upon the predictability of the approaches. Date: Thursday, December 12, 2019 Time: 9:00 A.M. Place: ARMS 1103

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Seminar Notice for Yujie Wang's Preliminary Exam. Wednesday, Dec. 11, at 12:00, in ARMS 1103 The review and exam will also be in ARMS 1103
by Son, Rosemary E 09 Dec '19

09 Dec '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Oxidation Kinetics of the Cr2AlC MAX Phase" By Yujie Wang Purdue MSE Preliminary Exam Advisor: Professor Kenneth H. Sandhage ABSTRACT Currently, the MAX phase materials have received significant attention from scientists because of their promising practical application. The unique nano-layered structure provides a useful combination of metallic and ceramic properties. For example, MAX phases are typically characterized as being thermally and electrically conductive, plastically deformable, machinable, and thermal shock resistant like metals; as well as having high elastic moduli, excellent high-temperature mechanical properties, and good oxidation and hot corrosion resistance like ceramics. Among all the MAX phases, Cr2AlC is a thermodynamically stable ternary compound with hexagonal structure. The chromium aluminium carbide (Cr2AlC) exhibits excellent mechanical properties and good oxidation and hot corrosion resistance due to the formation of dense adherent α-Al2O3 protective layer. All those unique properties along with the excellent oxidation resistance make Cr2AlC an attractive material for high-temperature applications. However, it will be necessary to understand the oxidation mechanism and corresponding kinetics of Cr2AlC in order to predict the long-time performance at elevated temperatures. This is, in turn, implies that the oxidation kinetics need to be well understood. However, the kinetic behavior of Cr2AlC is still under controversy. In this document, the mechanisms of isothermal oxidation of Cr2AlC will be studied, and the corresponding rate-limiting steps would be reviewed. Date: Wednesday, December 11, 2019 Time: 12:00 P.M. Place: ARMS 1103

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MSEE & ARMS Lab Classifications
by MSE Safety 09 Dec '19

09 Dec '19

Hello MSE Researchers, Here is a spreadsheet of MSEE & ARMS lab classifications and their PIs as requested by a few students. I hope this is helpful. Regards, Jenni

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Seminar Notice for Amrita Sen Wednesday, Dec. 11 at 12:30, in ARMS 1021. Review will be at 2:30 (for the student) Exam will begin at 3:00 All in ARMS 1021
by Son, Rosemary E 09 Dec '19

09 Dec '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Atom Probe Tomography of Bulk Oxides" By Amrita Sen Purdue MSE Preliminary Exam Advisors: Professor Anter A. El-Azab and Professor Janelle P. Wharry ABSTRACT Atom Probe Tomography (APT) is a 3D microscopy technique that can provide atom-byatom spatial and chemical quantification of a needle-shaped sample. The technique is well established for use with metals. However, APT of oxide/semiconductor/insulating materials is not trivial. This review will specifically focus on APT of bulk oxides. The optical and absorption properties of oxide materials influence whether successful laser absorption, field evaporation, and accurate chemical quantification of the material can be achieved with this technique. Factors such as laser energy and laser wavelength influence field evaporation and measured chemistry, and therefore must be optimized for each oxide respectively. This paper will review previous parametric studies of bulk oxides with APT and seek to identify any trends in field evaporation behavior and chemical analysis of these types of materials with this technique. Date: Wednesday, December 11, 2019 Time: 12:30 P.M. Place: ARMS 1021 School of Materials Engineering Purdue University Neil Armstrong Hall of Engineering 701 West Stadium Ave. Room 2200 West Lafayette, IN 47907 765-494-4105 [PU150]

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Seminar Notice for Yifan Wu's Preliminary Exam. Seminar, Wednesday, Dec. 11, at 8:00 a.m., in ARMS 1109
by Son, Rosemary E 09 Dec '19

09 Dec '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Liquid Metal Embrittlement Induced by Gallium-based Liquid Metal" By Yifan Wu Purdue MSE Preliminary Exam Advisors: Professor Carol A. Handwerker and Professor John E. Blendell ABSTRACT Liquid metal embrittlement (LME) is a phenomenon in which a normally ductile metal or alloy experiences loss of ductility when stressed while in contact with a liquid metal. Ga is of particular interest in the study of LME due to its relatively low melting point. Although LME has been discovered for over a century, the mechanism behind is yet fully understood. Current consensus on the occurrence of LME is decrease in interatomic bond strength induced by the adsorption of liquid metal. Recent progress in nanoscale characterization techniques, such as synchrotron X-ray radiography and in situ TEM shows that the Ga penetration-induced dislocation movement and localized plasticity at the penetration front of gallium. Advanced synchrotron X-ray tomography reveals the dependence of Ga liquid metal penetration on grain boundary energy. Computational methods provide an alternative approach in studying LME at an atomic scale. Atomistic simulation results show the effect of applied stress on grain boundary penetration at an atomistic scale as well as dislocation movement along the grain boundary. A new model, dislocation climb model, was proposed based on this observation to explain the occurrence and propagation of cracks in LME. Key words: Liquid metal embrittlement, gallium liquid metal, grain boundary penetration Date: Wednesday, December 11, 2019 Time: 8:00 A.M. Place: ARMS 1109 School of Materials Engineering Purdue University Neil Armstrong Hall of Engineering 701 West Stadium Ave. Room 2200 West Lafayette, IN 47907 765-494-4105 [PU150]

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