November 2019 - Msepostdoc-list

Seminar Reminder for Lorena Alzate Vargas's Ph.D. Final Exam. Monday, Nov. 25, 2019, at 11:00 a.m., in HAMP 2117. "Structural Properties and Local Chain Dynamics of Polymeric Materials Using Molecular Dynamics"
by Son, Rosemary E 22 Nov '19

22 Nov '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Structural Properties and Local Chain Dynamics of Polymeric Materials Using Molecular Dynamics" By L. Lorena Alzate Vargas Purdue MSE Ph.D. Final Exam Advisor: Professor Alejandro Strachan ABSTRACT The use of atomistic level simulations like molecular dynamics are becoming a key part in the process of materials discovery, optimization and development since they can provide complete description of a material and contribute to understand the response of materials under certain conditions or to elucidate the mechanisms involved in the materials behavior. We will discuss to cases in which molecular dynamics simulations are used to characterize and understand the behavior of materials: i) prediction of properties of small organic crystals in order to be implemented in a multiscale modeling framework which objective is to predict mechanically induced amorphization without experimental input other than the molecular structure and ii) characterization of temperature dependent spatio-temporal domains of high mobility torsions in several bulk polymers, thin slab and isolated chains; strikingly we observe universality in the percolation of these domains across the glass transition. However, as in any model, validation of the predicted results against appropriate experiments is a critical stage, especially if the predicted results are to be used in decision making. Various sources of uncertainties alter both modeling and experimental results and therefore the validation process. We will present molecular dynamics simulations to assess uncertainties associated with the prediction of several important properties of thermoplastic polymers; in which we independently quantify how the predictions are affected by several sources. Interestingly, we find that all sources of uncertainties studied influence predictions, but their relative importance depends on the specific quantity of interest. Date: Monday, November 25, 2019 Time: 11:00 A.M. Place: HAMP 2117

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MSE 690 Beth Holloway 11-22, 3:30 PM, ARMS 1010
by Ku Blanco, Aury Y 22 Nov '19

22 Nov '19

Hi all, Forwarding on behalf of Jessica Sargent + MSEGSA, please plan to attend: [cid:image004.jpg@01D59BA9.8D617390] Grad Students, if you are interested in joining Dr. Holloway for lunch next Friday- please reach out to me for more information. 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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Seminar Notice for Elizabeth Laskowski's Prelim. Monday, Dec. 2 at 11:00 a.m., in ARMS 1028. Review same day, at 12:00, in ARMS 2237. Exam, at 12:30, in ARMS 2237 " High Temperature Dissolution Kinetics of Solids in Molten Chloride Salts"
by Son, Rosemary E 21 Nov '19

21 Nov '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "High Temperature Dissolution Kinetics of Solids in Molten Chloride Salts" By Elizabeth A. Laskowski Purdue MSE Preliminary Exam Advisor: Professor Kenneth H. Sandhage ABSTRACT Chloride based molten salts are of growing interest as heat transfer fluids and thermal energy storage media for concentrated solar power and as solvent baths for spent nuclear fuel processing and precious metal recovery. Sea-derived salts are especially attractive as they offer low cost, abundance, and nontoxic waste in addition to high temperature stability (>650C), low viscosity, and high heat capacity. As new engineering solutions seek to utilize molten chlorides, a significant barrier is finding cost-effective materials that can contain the hot fluids over extended service times due to the corrosive nature of the salts. Sparse literature deeply explores the corrosion kinetics observed for these fluids and generally kinetic assumptions are oversimplified and based purely on static corrosion tests. Literature exploring the kinetics of dissolution in molten oxides lends established models to describe the dissolution behavior observed in molten chloride studies. Understanding the kinetics of material dissolution in these salts will serve new material development to meet the demands of applications. Date: Monday, December 2, 2019 Time: 11:00 A.M. Place: ARMS 1028 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 Reminder for R. G. Sreekar Annadanam's Preliminary Exam. Seminar Thursday, Nov. 21, 8:00 a.m., in ARMS 1103. "Void Formation and Evolution in Irradiated Metals Studied by Phase-Field Approach"
by Son, Rosemary E 20 Nov '19

20 Nov '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Void Formation and Evolution in Irradiated Metals Studied by Phase-Field Approach" By Rayaprolu Goutham Sreekar Annadanam Purdue MSE Preliminary Exam Advisor: Professor Anter El-Azab ABSTRACT The safe and efficient operation of nuclear reactors requires the structural materials to be stable chemically, microstructurally and dimensionally under energetic particle irradiation. An ubiquitous phenomenon that occurs in many structural alloys in nuclear reactors is volumetric swelling. This phenomenon is primarily attributed to the nucleation and growth of voids and bubbles filled with transmutation gases such as helium . Early attempts to model this phenomenon involved the use of the classical nucleation theory and reaction rate theory models to capture the nucleation and growth kinetics, respectively, and correlate the observed effects with the irradiation dose rate and temperature. However, these models suffered certain limitations associated with the requirement of homogeneity of the irradiated material and defect fields, and were thus not adequately reliable in explaining the experimental results and in making predictions. Relatively recently, the phase field approach was introduced with the goal to capture the concurrent nucleation and growth of voids and bubbles under the condition of dynamic point defect production by atomic collision cascades in irradiation environments. Of particular interest in this study are the phase field models for void nucleation and growth. In the literature, these models can be primarily classified into two types, those based upon Cahn-Hilliard type equations and others based upon combined Cahn-Hilliard and Allen-Cahn equations. While these models have been well tested, they are not able to provide quantitative predictions yet due to the yet-to-be completed theoretical underpinning of the phase field model parameters, especially the Allen-Cahn mobility. Such parameters require matching with the so-called sharp interface models, which represent the physics of void growth better. In addition to fixing the phase field model parameters, such a matching is also required to guarantee physical and thermodynamic consistency of the phase field approach. In this paper, I review the existing phase field models and discuss further steps to make the phase field consistent with sharp interface theory. Date: Thursday, November 21, 2019 Time: 8:00 A.M. Place: ARMS 1103

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Seminar Reminder for Yash Pachaury's Preliminary Exam. Tuesday, Nov. 19, at 8:00 a.m., in ARMS 1021. "A Survey on Microstructure Analysis and Synthesis using Statistical Techniques
by Son, Rosemary E 18 Nov '19

18 Nov '19

Please consider attending the following tomorrow morning at 8:00 a.m. MATERIALS ENGINEERING SEMINAR "A Survey on Microstructure Analysis and Synthesis using Statistical Techniques" By Yash Pachaury Purdue MSE Preliminary Exam Advisor: Professor Anter El-Azab ABSTRACT Microstructure analysis and synthesis forms an essential part of establishing structure-property relationships of materials. Correlations between the different microstructural features, such as grain boundaries, inclusions and other defects, and the physical behavior of materials can reveal insights into the underlying mechanisms responsible for their observed behavior. For developing high fidelity computational tools, it becomes essential to extract different microstructural characteristics for studying the behavior of materials at different length and time scales. These microstructure characteristics can be utilized to reconstruct virtual microstructures to be used as an input to develop accurate microstructure dependent numerical models. This paper provides a review of different statistical techniques of microstructure analysis and synthesis to determine effective properties of multiphase materials and resolve microstructure dependent fields by explicitly introducing these features from experimental measurements into predictive models. This review provides an understanding of the microstructure correlation functions and the different paradigms such as phase recovery, simulated annealing and Markov random field-based approaches, which use these microstructural descriptors to reconstruct virtual microstructures to model the physical behavior of materials, including their effective structural response. Some areas of future research have been determined based on a critical assessment of different techniques. Date: Tuesday, November 19, 2019 Time: 8:00 A.M. Place: ARMS 1021

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Seminar Notice for Ziyun Huang's Preliminary Exam, Wednesday, Nov. 27, at 1:00, in ARMS 1021 " Thermodynamically-driven Massive Spalling in Solder Joints"
by Son, Rosemary E 18 Nov '19

18 Nov '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Thermodynamically-driven Massive Spalling in Solder Joints" By Ziyun Huang Purdue MSE Preliminary Exam Advisors: Professor Carol A. Handwerker and Professor John E. Blendell ABSTRACT Solder joint plays an important role in present packaging industry and has a great impact on overall reliability property of chips. This review will mainly focus on massive spalling phenomenon in solders and its thermodynamic driving force. The necessary condition for spalling to happen is that at least one of the active components has limited amount, and local equilibrium changes as the reactive constituent is consumed. Specifically, massive spalling results from two mechanism (1) grain boundary penetration and (2) microvoids aggregation. Both high-lead and lead-free solders will be considered due to environmental concern of lead. For each case, industrial methods to inhibit massive spalling have been discussed. However, increased interfacial energy as a consequence of spalling has never been directly proved, and more experiments are needed to further understand this problem. Date: Wednesday, November 27, 2019 Time: 1:00 P.M. Place: ARMS 1021

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Seminar Notice for Lorena Alzate Vargas's Ph.D. Final Exam. Monday, Nov. 25, 2019, at 11:00 a.m., in HAMP 2117. "Structural Properties and Local Chain Dynamics of Polymeric Materials Using Molecular Dynamics"
by Son, Rosemary E 18 Nov '19

18 Nov '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Structural Properties and Local Chain Dynamics of Polymeric Materials Using Molecular Dynamics" By L. Lorena Alzate Vargas Purdue MSE Ph.D. Final Exam Advisor: Professor Alejandro Strachan ABSTRACT The use of atomistic level simulations like molecular dynamics are becoming a key part in the process of materials discovery, optimization and development since they can provide complete description of a material and contribute to understand the response of materials under certain conditions or to elucidate the mechanisms involved in the materials behavior. We will discuss to cases in which molecular dynamics simulations are used to characterize and understand the behavior of materials: i) prediction of properties of small organic crystals in order to be implemented in a multiscale modeling framework which objective is to predict mechanically induced amorphization without experimental input other than the molecular structure and ii) characterization of temperature dependent spatio-temporal domains of high mobility torsions in several bulk polymers, thin slab and isolated chains; strikingly we observe universality in the percolation of these domains across the glass transition. However, as in any model, validation of the predicted results against appropriate experiments is a critical stage, especially if the predicted results are to be used in decision making. Various sources of uncertainties alter both modeling and experimental results and therefore the validation process. We will present molecular dynamics simulations to assess uncertainties associated with the prediction of several important properties of thermoplastic polymers; in which we independently quantify how the predictions are affected by several sources. Interestingly, we find that all sources of uncertainties studied influence predictions, but their relative importance depends on the specific quantity of interest. Date: Monday, November 25, 2019 Time: 11:00 A.M. Place: HAMP 2117

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Seminar Notice for Yash Pachaury's Preliminary Exam. Tuesday, Nov. 19, at 8:00 a.m., in ARMS 1021. "A Survey on Microstructure Analysis and Synthesis using Statistical Techniques
by Son, Rosemary E 18 Nov '19

18 Nov '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "A Survey on Microstructure Analysis and Synthesis using Statistical Techniques" By Yash Pachaury Purdue MSE Preliminary Exam Advisor: Professor Anter El-Azab ABSTRACT Microstructure analysis and synthesis forms an essential part of establishing structure-property relationships of materials. Correlations between the different microstructural features, such as grain boundaries, inclusions and other defects, and the physical behavior of materials can reveal insights into the underlying mechanisms responsible for their observed behavior. For developing high fidelity computational tools, it becomes essential to extract different microstructural characteristics for studying the behavior of materials at different length and time scales. These microstructure characteristics can be utilized to reconstruct virtual microstructures to be used as an input to develop accurate microstructure dependent numerical models. This paper provides a review of different statistical techniques of microstructure analysis and synthesis to determine effective properties of multiphase materials and resolve microstructure dependent fields by explicitly introducing these features from experimental measurements into predictive models. This review provides an understanding of the microstructure correlation functions and the different paradigms such as phase recovery, simulated annealing and Markov random field-based approaches, which use these microstructural descriptors to reconstruct virtual microstructures to model the physical behavior of materials, including their effective structural response. Some areas of future research have been determined based on a critical assessment of different techniques. Date: Tuesday, November 19, 2019 Time: 8:00 A.M. Place: ARMS 1021

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Seminar Notice for Jorge Ramirez Velasco's Ph.D. Final Exam. Wednesday, Nov. 20, at 9:00 a.m., in ARMS 3115
by Son, Rosemary E 18 Nov '19

18 Nov '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "The Effect of Biofuel Impurities on the Hot Corrosion of Yttria Stabilized Zirconia Thermal Barrier Coatings" By Jorge H. Ramirez Velasco Purdue MSE Ph.D. Final Exam Advisor: Professor Rodney W. Trice ABSTRACT Aircraft propulsion and industrial power generation have highlighted the critical role of gas turbines in modern society. Currently, components for these applications must withstand temperatures of at least 1400°C when operating within the combustor and the high-pressure sections of a gas turbine engine. With superalloys operating at its maximum capacity, ceramic multilayered materials systems known as thermal barrier coatings (TBCs) provide thermal and environmental protection to the engine's components. However, the introduction of biofuels into gas turbines applications has come with new challenges. The contaminants found in military and commercial biofuels are known to include oxides of alkali and alkaline earth metals and silicon oxides. While calcium-magnesium-aluminum silicates (CMAS) are typically ingested as particulate in volcanic ash and desert sand theaters, the impurity list in biofuels includes the necessary elements to form CMAS without exposure to any specific environment. CMAS is particularly destructive for operating temperatures above its melting temperature (~1250°C), mainly reducing yttria-stabilized zirconia (YSZ) TBCs lifetimes. Thus, identification of the corrosive compounds produced by the interaction of biofuel contaminants/TBCs and a specific understanding of its adverse effect is mandatory to avoid the failure of gas turbines. In this work, solutions containing the impurities of interest are prepared and sprayed onto TBCs simulating the deposit of the impurities during combustion. Subsequently, the TBCs are subject to thermal gradient testing up to 1400°C, and their microstructures evaluated. Date: Wednesday, November 20, 2019 Time: 9:00 A.M. Place: ARMS 3115

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Seminar Notice for R. G. Sreekar Annadanam's Preliminary Exam. Seminar Thursday, Nov. 21, 8:00 a.m., in ARMS 1103. "Void Formation and Evolution in Irradiated Metals Studied by Phase-Field Approach"
by Son, Rosemary E 18 Nov '19

18 Nov '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Void Formation and Evolution in Irradiated Metals Studied by Phase-Field Approach" By Rayaprolu Goutham Sreekar Annadanam Purdue MSE Preliminary Exam Advisor: Professor Anter El-Azab ABSTRACT The safe and efficient operation of nuclear reactors requires the structural materials to be stable chemically, microstructurally and dimensionally under energetic particle irradiation. An ubiquitous phenomenon that occurs in many structural alloys in nuclear reactors is volumetric swelling. This phenomenon is primarily attributed to the nucleation and growth of voids and bubbles filled with transmutation gases such as helium . Early attempts to model this phenomenon involved the use of the classical nucleation theory and reaction rate theory models to capture the nucleation and growth kinetics, respectively, and correlate the observed effects with the irradiation dose rate and temperature. However, these models suffered certain limitations associated with the requirement of homogeneity of the irradiated material and defect fields, and were thus not adequately reliable in explaining the experimental results and in making predictions. Relatively recently, the phase field approach was introduced with the goal to capture the concurrent nucleation and growth of voids and bubbles under the condition of dynamic point defect production by atomic collision cascades in irradiation environments. Of particular interest in this study are the phase field models for void nucleation and growth. In the literature, these models can be primarily classified into two types, those based upon Cahn-Hilliard type equations and others based upon combined Cahn-Hilliard and Allen-Cahn equations. While these models have been well tested, they are not able to provide quantitative predictions yet due to the yet-to-be completed theoretical underpinning of the phase field model parameters, especially the Allen-Cahn mobility. Such parameters require matching with the so-called sharp interface models, which represent the physics of void growth better. In addition to fixing the phase field model parameters, such a matching is also required to guarantee physical and thermodynamic consistency of the phase field approach. In this paper, I review the existing phase field models and discuss further steps to make the phase field consistent with sharp interface theory. Date: Thursday, November 21, 2019 Time: 8:00 A.M. Place: ARMS 1103

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