December 2017 - Msepostdoc-list

Seminar Notice for Sae Matsunaga's Prelim Exam; Seminar Monday Dec. 11, at 9:30 a.m., in ArMS 3115; Exam, same day, at 1:30, in ArmS 2009. "Segregated-Assister Shearing of the G'Phase in Ni-Based Superalloys"
by Son, Rosemary E 04 Dec '17

04 Dec '17

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Segregated-Assister Shearing of the G'Phase in Ni-Based Superalloys" By Sae Matsunaga Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Michael S. Titus ABSTRACT Ni-based superalloys have been developed and used for over 60 years for high temperature applications due to their superior material properties; such as, high temperature strength, resistance to creep, high thermal/mechanical fatigue strength, and excellent oxidation resistance. Much of the high temperature strength is due to the presence of a high volume fraction (~70%) of *'-(ordered fcc/L12) precipitates, which are embedded coherently in a ***fcc/A1) matrix. These materials are widely used in gas turbines for aircraft engines, land-based turbines for natural gas-operated power plants, rocket engines, and other applications where extreme environments are present. Over the decades, the high temperature deformation mechanisms of Ni-based superalloys have been studied, and it has been revealed that the deformation mechanisms of Ni-based superalloys strongly depend on certain microstructural features (*' volume fraction, size, and shape) and alloy composition. Recently, shearing of the *' precipitates by partial dislocations has been identified as the rate-limiting creep deformation mechanism at low temperature and high stresses in some Ni-based superalloys. The current understanding of *' shearing will be discussed with special focus on the planar defects in the *' phase such as superlattice intrinsic/ extrinsic stacking faults, antiphase boundaries, and microtwins. To understand the relationship between defects in *' phase and primary alloy elements, high resolution EDX would be carried out for further investigation of segregation at faults and microtwins. This would bring a more complete understanding of the deformation mechanisms and segregation behavior of essential alloying elements would bring new insight to guided alloy design and reveal the underlying mechanisms and driving forces responsible for shearing of the *' phase. Date: Monday, December 11, 2017 Time: 9:30 A.M. Place: ARMS 3115

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Seminar Notice for Congying Wang's Preliminary Exam: Seminar, Monday, Dec. 11, at 8:30 a.m., in ARMS 3115; Exam same day at, 10:00, in ARMS 2326. " Slip Systems in Beta-Sn: to Relate Dislocations and Grain Nucleation"
by Son, Rosemary E 04 Dec '17

04 Dec '17

Please consider attending the following: MATERIALS ENGINEERING SEMINAR “Slip Systems in Beta-Sn: to Relate Dislocations and Grain Nucleation” By Congying Wang Purdue MSE Ph.D. Preliminary Exam Advisors: Professors Carol A. Handwerker and John E. Blendell ABSTRACT β-Sn coatings are widely used in the electronic industry to provide better solderability to prevent oxidation.The formation and growth of whiskers are known to be a stress relaxation response of tin films, some of which can grow up to millimeter-long and cause short circuits in electronics. Previous studies indicate that shallow grains are critical for whisker growth, acting as preferred sites for growth compared to columnar grains. Whiskers have been observed to form through recrystallization along grain boundaries (GB) during thermal cycling of as-solidified films of tin-silver-copper alloys (SAC305). In this study, changes in surface morphology were quantified in large-grained tin films during thermal cycling (-35◦C/+85◦C) from the 1st cycle, which suggested a relationship between local dislocation activity and low-angle boundary formation. In order to relate the underlying mechanism of the dislocation motion and the grain nucleation, slip behav-iors in β-Sn has been reviewed. At least 12 nonequivalent families of slip systems have been reported due to the anisotropy of β-Sn. Unlike FCC materials, the crystallography theory and dislocation energy cannot fully explain why specific slip system was activated, or predict which slip system will become active. Other factors influencing the slip behaviors are temperature, grain size, and grain boundary. Date: Monday, December 11, 2017 Time: 8:30 A.M. Place: ARMS 3115

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Reminder Today: MSE 690 Seminar Speaker Dr. Brian Bennett, Monday, December 4, 2017 ARMS 1010 3:30 pm
by Coar, Stacey L 04 Dec '17

04 Dec '17

Good morning, MSE 690 guest speaker Dr. Brian Bennett, Program Officer for Electromagnetic Materials Office of Naval Research, will be visiting on Monday, December 4. Please see his attached abstract, I hope to see you all there. [cid:image001.png@01D3685D.43D6E380] Stacey Stacey Coar Secretary/Development Assistant School of Materials Engineering Purdue University Neil Armstrong Hall of Engineering 701 West Stadium Ave. Room 2300 West Lafayette, IN 47907 765-494-4100 scoar(a)purdue.edu<mailto:scoar@purdue.edu>

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Reminder for Yen-Yu (Winston) Chen's Preliminary Exam. Seminar, Tuesday, Dec. 5, at 1:30 p.m., in ARMS 1109; Exam same day at 3:00 in ARMS 2237. "Flexible Gas Sensors for Monitoring Volatile Organic Compounds"
by Son, Rosemary E 04 Dec '17

04 Dec '17

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Flexible Gas Sensors for Monitoring Volatile Organic Compounds" By Yen-Yu Chen Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Lia A. Stanciu ABSTRACT Two-dimensional (2D) transition metal dichalcogenides (TMDCs) are considered as a new class of sensing materials because of their flexible layered structure, high specific surface area, and good semiconducting properties. A gas sensor capable of operating at room temperature is appealing because it requires a simple fabrication process and low power consumption. Herein, a review of various sensing materials, metal-oxide semiconductors, carbon-based materials, and TMDCs, for the detecting features of different life-affecting and environment-impacting gases, including volatile organic compounds (VOCs), inorganic gases (NH3 and NO2), and ethylene, will be presented. Then, the fabrication methods of TMDCs, particularly 2D MoS2 (layered nanoflake), will be introduced. These reviews suggest that (a) LPE is one of most promising cost-effective methods to synthesize 2D TMDC gas-sensing materials in a mass-production manner and (b) surface modification is required for TMDCs to detect gases effectively at room temperature. Indeed, preliminary research results indicate that the gas sensors made of Au-decorated LPE-MoS2 exhibit superior ability to sense extremely low concentrations of VOCs at room temperature. A series of LPE-TMDCs will be further studied for the development of high-performance, room-temperature gas sensors. Date: Tuesday, December 5, 2017 Time: 1:30 P.M. Place: ARMS 1109

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Reminder for Sathish Kumar Ranganathan's Prelim. Seminar, Tuesday, Dec. 5, at 9:30 in HAMP 1266; Exam same day, at 1:30, in ARMS 3001 "Durable Icephobic Coatings for Aluminum Substrates"
by Son, Rosemary E 04 Dec '17

04 Dec '17

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Durable Icephobic Coatings for Aluminum Substrates" By Sathish Kumar Ranganathan Purdue MSE Ph.D. Preliminary Exam Advisors: Professors Jeffery P. Youngblood and John A. Howarter ABSTRACT Development of durable ice-phobic coatings and mitigation of ice accumulation on solid surfaces has proven to be a challenging task in the past decade. Considering the current limitations to the state of the art, development of durable superhydrophobic surfaces which could deliver less ice accretion and low ice adhesion strength is an important research milestone. Improving experimental understating of ice phobic performance, such as the correlation between ice adhesion strength and ice removal conditions, as well as the role of surface wetting properties to the rate of ice accumulation would be quite valuable. Therefore, highly durable Fluoro-Ethylene-Alkyl-Vinyl-Ether (FEVE) based slippery and superhydrophobic coating will be developed to study its durability at extreme ageing conditions and retention of icephobic performance will be validated to understand potential benefits for industrial applications. Date: Tuesday, December 05, 2017 Time: 9.30 A.M. Place: HAMP 1266

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Reminder: MSE 690 Seminar Speaker Dr. Brian Bennett, Monday, December 4, 2017 ARMS 1010 3:30 pm
by Coar, Stacey L 01 Dec '17

01 Dec '17

Good morning, MSE 690 guest speaker Dr. Brian Bennett, Program Officer for Electromagnetic Materials Office of Naval Research, will be visiting on Monday, December 4. Please see his attached abstract, I hope to see you all there. [cid:image001.png@01D3685D.43D6E380] Stacey Stacey Coar Secretary/Development Assistant School of Materials Engineering Purdue University Neil Armstrong Hall of Engineering 701 West Stadium Ave. Room 2300 West Lafayette, IN 47907 765-494-4100 scoar(a)purdue.edu<mailto:scoar@purdue.edu>

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Seminar Notice for Duo Huang's Preliminary Exam: Seminar, Friday, Dec. 8, at 1:30, in HAMP 1113; Exam, same day, at 3:00, in ARMS 3001. "Fe-Mn Alloys as Biodegradable Metallic Materials"
by Son, Rosemary E 01 Dec '17

01 Dec '17

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Fe-Mn Alloys as Biodegradable Metallic Materials" By Duo Huang Purdue MSE Ph.D. Preliminary Exam Advisors: Professors David Johnson and Professor Matthew J. M. Krane ABSTRACT Biodegradable metallic materials are considered promising candidates to replace traditional permanent implants. Among all the metallic materials studied, Fe-Mn alloys show their potential to be a new type of biodegradable alloys. In this study, the design strategy of Fe-Mn alloys and the factors affecting Fe-Mn alloys' biodegradation behavior as well as mechanical properties are discussed. For alloy designing, adding less noble elements to form a solid solution and adding nobler elements to form intermetallic phases can both accelerate corrosion rates. The mechanical properties of Fe-Mn alloys are also discussed in the study. The effect of Mn concentration and intermetallic phases can modify alloys' mechanical properties. Considering all the factors discussed, a type of high manganese steel, Hadfield steel with 1.0 - 1.4 wt.% C and 10 - 14 wt.% Mn is proposed. Its unique properties make it possible to improve corrosion rate and mechanical properties at the meantime. Date: Friday, December 8, 2017 Time: 1:30 P.M. Place: HAMP 1113

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Seminar Notice for Chengzi Huang's Preliminary Exam. Seminar, Friday, Dec. 8, at 12:00, in ARMS 3115; Exam, same day, at 1:30, in ARMS 2222. "MEMS Actuator Based on Dopant-Driving Thin Film Perovskite Nickelate"
by Son, Rosemary E 01 Dec '17

01 Dec '17

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "MEMS Actuator Based on Dopant-Driving Thin Film Perovskite Nickelate" By Chengzi Huang Purdue MSE Ph.D. Preliminary Exam Advisors: Professors Dana Weinstein and Shriram Ramanathan ABSTRACT Rare earth nickelate exhibits a series of fantastic properties based on its abnormal metal-insulator transition (MIT) phenomenon, which has attracted huge concerns from different areas since 1970s. Except for traditional thermally driven method for phase transition materials, electron doping is found to be another effective driving mechanism which origins from the strong correlation of electrons in the [cid:image001.png@01D36A86.73247F50] orbital of Ni2+ cation. Giant changes of resistivity and lattice parameter are observed during the phase transition. In this work, the crystal structures and phase transition mechanisms of perovskite nickelates is being discussed, and based on their performance, NdNiO3 (NNO) is selected to be the core material for MicroElectroMechanical Systems (MEMS) actuators. Synthesis as well as characterization method are also introduced to further understand and utilize its unique properties in actuators. Traditional actuation materials are being discussed in details and are compared with NNO to give a better idea to estimate the performance of NNO actuator. Although there is no record of perovskite materials utilized in actuation area, NNO is a strong candidate based on its unique properties such as high induced strain, giant resistivity change, and fast phase transition speed. This study also offers us an opportunity to explore the mechanical properties of perovskite nickelates associated with the phase transition, and their application in MEMS. Date: Friday, December 8, 2017 Time: 12:00 P.M. Place: ARMS 3115

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Seminar Notice for Gyuchul Park's Preliminary Exam. Seminar, Friday, Dec. 8, at 8:30 a.m., in ARMS 1028; Exam same day, in ARMS B197. "Evaluation of Radiation Damage in Materials Using Extended X-ray Absorption Fine Structures (EXAFS)"
by Son, Rosemary E 01 Dec '17

01 Dec '17

Please consider attending the following: MATERIALS ENGINEERING SEMINAR “Evaluation of Radiation Damage in Materials Using Extended X-ray Absorption Fine Structures (EXAFS)” By Gyuchul Park Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Maria A. Okuniewski ABSTRACT With an effort to substitute low-enriched uranium (defined as less than 20% 235U) for highly enriched uranium (defined as more than 20% 235U) by Reduced Enrichment for Research and Test Reactors program launched in 1978, uranium molybdenum (U-Mo) alloy has been considered as a promising nuclear fuel material for future research reactors. U-Mo alloy fuel displays great irradiation behavior because, γ-phase uranium, stable above 771°C, can be obtained at the operating temperature of research reactors (below 250°C) by alloying molybdenum in uranium under quenching conditions. An understanding of the irradiation behavior of U-Mo alloy fuel is crucial in order to improve the fuel performance. Accordingly, Extended X-ray Absorption Fine Structure (EXAFS), which uses a synchrotron x-ray source, is a useful experimental technique to study radiation damage on the atomic level in materials because changes in local structure such as atomic distance and coordination number can be probed within 5-6 Å from an absorbing atom. In the following document, the general radiation-induced defects observed in irradiated materials are reviewed. Then, the background of EXAFS is briefly introduced and followed by a discussion of how EXAFS can be utilized to investigate radiation damage in materials. Keywords: Radiation Damage, Uranium-Molybdenum Monolithic Fuel Alloys, Extended X-ray Absorption Fine Structure (EXAFS). Date: Friday, December 8, 2017 Time: 8:30 A.M. Place: ARMS 1028

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Seminar Reminder for Indrani Biswas's Preliminary Exam, Monday, Dec. 4, at 12:30 p.m., in ARMS 3115, Exam Dec 4, at 2:00, in ARMS 2009. " Analysis of Sample Size Effects on Strength of Metals and Alloys Through Micropillar Compression Testing"
by Son, Rosemary E 01 Dec '17

01 Dec '17

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Analysis of Sample Size Effects on Strength of Metals and Alloys Through Micropillar Compression Testing" By Indrani Biswas Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Kevin P. Trumble ABSTRACT Yield strength of metals and alloys has long been known as a material property with little or no dependence on specimen size. However, through micropillar compression testing (MCT) it was revealed that, strength of micron-sized single crystal pillars was much larger than of bulk specimens and scaled with the pillar diameter. The paper analyses the theory of dislocation starvation; which assumes increased dislocation annihilation from sample surface as the reason for such high strengths. It was found that the model predicts near zero dislocation densities shortly after the onset of plasticity which is unrealistic. Polycrystals under MCT showed unexpected weakening when the sample size was few times the grain diameter. Two competing theories for weakening have been compared. The first attributes it to occurrence of grain boundary sliding and the second assumes that surface grains provide lower resistance to dislocation motion than those in the interior. Higher fraction of surface to bulk grains in smaller samples is probably responsible for the loss in strength. The analysis presented was that since surface grains are under less constraint, they are also more prone to sliding. So, the weakening can be a combined effect of the two mechanisms. Simulation of polycrystal deformation with different surface to volume ratio was suggested to validate the hypothesis. Date: Monday, December 4, 2017 Time: 12:30 P.M. Place: ARMS 3115

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