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Seminar Reminder for Daniel Klenosky's Ph.D. Final Exam. Seminar, Monday, April 30, in ARMS 1028, at 2:30; Exam, same day, at 3:30, in ARMS 2326. " Large Strain Extrusion Machining of AA7050"
by Son, Rosemary E 26 Apr '18

26 Apr '18

This is a reminder that Daniel Klenosky's Ph.D. Final Seminar is Monday at 2:30, in ARMS 1028; Exam same day, in ARMS 2326, at 3:30. MATERIALS ENGINEERING SEMINAR "Large Strain Extrusion Machining of AA7050" By Daniel R. Klenosky Purdue MSE Ph.D. Final Exam Advisors: Professor David Johnson and Professor Kevin Trumble ABSTRACT Aluminum has remained among the most commonly-used materials for aerospace applications for the past 100 years. It is advantageous due to its relatively high strength, low weight, ease of forming, electrical and thermal conductivity, and low cost. Alloy 7050 is among highest strength aerospace-grade aluminum alloys and can be formed into a wide variety of shapes via extrusion, rolling, forging, and other processes. Unfortunately, consistent and homogenous process control can be difficult to achieve during these bulk forming operations due to the complexity of the Al-Zn-Mg-Cu alloy system. Poor process control can result in defects and/or inhomogeneous microstructures and properties, during either deformation or during post-deformation heat treatment. It is therefore desirable to learn more about the nature and mechanisms of microstructural evolution during bulk deformation processes, and it may also be desirable to seek alternative production methods where possible. Large strain extrusion machining (LSEM) is a simultaneous cutting-extrusion process that has been applied to AA7050 in this work. It is a single-step deformation process that is used both as a tool to explore deformation in general, and also as a potential alternative method to produce AA7050-T7 plate, one of the most commonly used forms of the material. Experiments in this work include LSEM starting from different initial microstructural conditions and different deformation conditions. Specifically, hardened AA7050-T7451 material, which is typically impossible to process due to its high strength and low workability, has been processed via LSEM at an effective strain larger than 1 to create continuous AA7050 plate with very smooth surfaces in a single deformation step. Room temperature LSEM has also been applied in this work to produce plate from O-tempered, as-cast, and as-homogenized AA7050. Results from experiments with these softer materials show the limitations of the LSEM process. Sticking friction, especially at slow cutting speeds, causes problems that lead to built-up edges at the strip-tool interfaces and poor surface quality. While continuous strips with good surface quality is possible for both annealed and as-homogenized material, careful balance must be maintained between cutting quickly enough to limit sticking friction but slowly enough to limit strain rate and adiabatic heating. After proper balance and control of these considerations was achieved, LSEM plate created from as-homogenized material was artificially aged successfully to create a product with properties similar to conventionally-rolled AA7050-T7451 plate. Date: Monday, April 30, 2018 Time: 2:30 P.M. Place: ARMS 1028

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Seminar Notice for Daniel Klenosky's Ph.D. Final Exam. Seminar, Monday, April 30, in ARMS 1028, at 2:30; Exam, same day, at 3:30, in ARMS 2326. " Large Strain Extrusion Machining of AA7050"
by Son, Rosemary E 23 Apr '18

23 Apr '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Large Strain Extrusion Machining of AA7050" By Daniel R. Klenosky Purdue MSE Ph.D. Final Exam Advisors: Professor David Johnson and Professor Kevin Trumble ABSTRACT Aluminum has remained among the most commonly-used materials for aerospace applications for the past 100 years. It is advantageous due to its relatively high strength, low weight, ease of forming, electrical and thermal conductivity, and low cost. Alloy 7050 is among highest strength aerospace-grade aluminum alloys and can be formed into a wide variety of shapes via extrusion, rolling, forging, and other processes. Unfortunately, consistent and homogenous process control can be difficult to achieve during these bulk forming operations due to the complexity of the Al-Zn-Mg-Cu alloy system. Poor process control can result in defects and/or inhomogeneous microstructures and properties, during either deformation or during post-deformation heat treatment. It is therefore desirable to learn more about the nature and mechanisms of microstructural evolution during bulk deformation processes, and it may also be desirable to seek alternative production methods where possible. Large strain extrusion machining (LSEM) is a simultaneous cutting-extrusion process that has been applied to AA7050 in this work. It is a single-step deformation process that is used both as a tool to explore deformation in general, and also as a potential alternative method to produce AA7050-T7 plate, one of the most commonly used forms of the material. Experiments in this work include LSEM starting from different initial microstructural conditions and different deformation conditions. Specifically, hardened AA7050-T7451 material, which is typically impossible to process due to its high strength and low workability, has been processed via LSEM at an effective strain larger than 1 to create continuous AA7050 plate with very smooth surfaces in a single deformation step. Room temperature LSEM has also been applied in this work to produce plate from O-tempered, as-cast, and as-homogenized AA7050. Results from experiments with these softer materials show the limitations of the LSEM process. Sticking friction, especially at slow cutting speeds, causes problems that lead to built-up edges at the strip-tool interfaces and poor surface quality. While continuous strips with good surface quality is possible for both annealed and as-homogenized material, careful balance must be maintained between cutting quickly enough to limit sticking friction but slowly enough to limit strain rate and adiabatic heating. After proper balance and control of these considerations was achieved, LSEM plate created from as-homogenized material was artificially aged successfully to create a product with properties similar to conventionally-rolled AA7050-T7451 plate. Date: Monday, April 30, 2018 Time: 2:30 P.M. Place: ARMS 1028

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MSE Seminar - Prof Maryam Ghazisaeidi - TODAY
by Donna Bystrom 20 Apr '18

20 Apr '18

Attached please find a seminar notice for Professor Maryam Ghazisaeidi from The Ohio State University. Seminar takes place today, 3:45PM, ARMS 1010

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Fwd: Nuclear Engineering Seminar
by Donna Bystrom 20 Apr '18

20 Apr '18

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Seminar Reminder for Daniel Kim's Ph.D. Final. Seminar, Friday, April 20, at 11:30, in ARMS 1103; Exam same day, at 12:30, in ARMS 2222. "Ultra Purification of Gallium by Zone Refining"
by Son, Rosemary E 19 Apr '18

19 Apr '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Ultra-Purification of Gallium by Zone Refining" By Daniel Kim Purdue MSE Ph.D. Final Exam Advisors: Professor David Johnson and Professor Kevin Trumble ABSTRACT High electron mobility is essential to improve two-dimensional electron gas (2DEG) quality in MBE grown AlGaAs/GaAs heterostrucutures. Recently, gallium purity was identified as limit to electron mobility in such structures. A laboratory horizontal zone refiner was constructed and procedures such as cleaning operation and handling/extracting samples were developed to suit needs for producing ultra-high purity gallium. One major problem is that the most of impurities are already below detection limit of current measurement techniques for starting high purity gallium. The 8N gallium (99.999999%, 10 ppb nominal purity) is the most commercially available pure gallium and measuring exact concentration becomes more difficult to determine the purity after zone refining. Thus, a last zone back-calculating approach was developed to characterize and to quantify purity in the purified zone. First, the performance of the zone refiner was evaluated using 5N gallium, intentionally doped with 14 different impurities (Cd, In, Sn, Ni, Cu, Zn, Pb, Bi, Ge, Au, Mn, S, Co, Al). Methods of measuring the effective partition coeffcients(keff) values for the first and the last zone were tested. All elements had keff values less than unity, but the values were increased as number of pass increased from n=1 to n=5 for the purified zone and n=5 for the last zone. The keff values assumed to be the same regardless of number of passes, but the zone length stability was a key factor affecting the keff values. One of the promising results from the 5N gallium study is that Mg and Sb having C0 below GDMS detection limit of 0.1 and 0.5 ppb were sufficiently raised to a useful detection limit of 20 and 1 ppb in the last zone. The last zone approach used in 5N gallium study was applied to the 8N gallium experiments and the purity in the first zone was back-calculated to estimate the overall purity. For the 1st 8N gallium experiment, the starting purity of >7N6 Ga was estimated to be >9N2 Ga based on 16 different elements after ten passes, whereas the starting purity of >7N4 was estimated to be >8N5 after nine passes for the 2nd 8N gallium experiment. However, C0 variations for In and Zn were determined from contamination and purity control studies. The C0,In varied from 120 to 0.3 ppb and from 10 to <0.5 ppb for Zn. Thus, there can be possible errors in estimating the purity for In and Zn when high C0 ingots are placed in the front zone. The expected In concentration in the purified zone was much less than below GDMS detection limit of 0.1 ppb, but the measured concentration showed 15 ppb for the 1st experiment. The same trend was observed for the Zn in the 2nd experiment. The measured concentration was 21 ppb, but the expected concentration was much less than detection limit of 0.5 ppb. Thus, recommendations for future experiment must be provided to overcome the C0 variation problems. Assuming that high C0 value of 500 ppb for In and Zn are located in the first 10 cm zone, the required number of passes to reach below detection limit is 24 for In and 20 for Zn. Practical number of passes is between 30 and 50 passes, which the starting purity of 6N gallium is expected to be purified to beyond the 10N gallium purity. Date: Friday, April 20, 2018 Time: 11:30 A.M. PURDUE MSE [cid:image003.png@01D3D7D3.279C6AB0] Place: ARMS 1103

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Seminar Reminder for Kayla Yano's Preliminary Exam. Seminar, Friday, April 20, at 2:00, in HAMP 2107; Exam same day, at 3:30, in ARMS 2222
by Son, Rosemary E 19 Apr '18

19 Apr '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "In Situ SEM and TEM Size-Effects in Ion Irradiated Materials" By Kayla Haruko Yano Purdue MSE Ph.D. Preliminary Exam Advisors: Professor Janelle P. Wharry and Professor Maria A. Okuniewski ABSTRACT Due to the shallow depth of ion irradiation damage, in situ SEM and TEM mechanical testing has been used to evaluate the irradiation effects on mechanical properties of irradiated materials. In turn, this small-scale testing can experience size-effects due to the microstructure-sample dimension relationship. This literature review provides a brief overview of the existing literature for three different sample geometries: micro-pillar compression, cantilever bending, and beam fracture testing. In depth analyses of the prevailing models for each geometry is also provided. Ultimately, this review concludes that coupling microstructural information with in situ mechanical testing can account for the size-effects in these geometries. Date: Friday, April 20, 2018 Time: 2:00 P.M. Place: HAMP 2107

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Seminar Reminder for Keyou Mao's Preliminary Exam. Seminar: Thursday, April 19, at 1:00, in ARMS 3115; Exam same day, at 2:30, in ARMS 2009
by Son, Rosemary E 18 Apr '18

18 Apr '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Microstructural Characterization and Micromechanical Testing of Laser Weld Repairs on Neutron Irradiated 304 Stainless Steel" By Keyou Mao Purdue MSE Ph.D. Preliminary Exam Advisors: Professor Janelle P. Wharry and Professor Xinghang Zhang ABSTRACT This study is intended for the assessment of microstructural and mechanical integrity of the laser weld repairs to highly neutron-irradiated, helium (He) containing AISI 304 Stainless Steel (SS). To satisfy the demands of the life extensions of Light Water Reactors (LWRs), welding is needed to repair the structural components of the reactor vessels. Conventional welding techniques such as gas tungsten arc welding has high-heat-input, leading the He coalescence into bubbles on the grain boundaries, which exacerbates cracking. The laser welding limits such issue by greatly reducing the heat input. There is consequently a critical need to assess the integrity of these welds for over-extended irradiation service. In this work, single laser welds are made on different plates of 304 SS irradiated in Experimental Breeder Reactor-II (EBR-II) reflector over a range of dose and He concentration conditions: ~1-24dpa with ~0.2-8 appm He, corresponding to ~0.5-2.5% swelling. A combination of transmission electron microscopy and electron backscattered diffraction is utilized to characterize the microstructure of the base, Heat Affected Zone (HAZ) and weld metal, for instance: voids, dislocations, grain structures, precipitates and chemical composition etc. Mechanical integrity in these regions is assessed by three major micromechanical testing methods: 1) Ex-situ and in-situ nanoindentation measures the hardness across the weldment; 2) Scanning Electron Microscopic (SEM) in-situ micropillar compression quantifies the dislocation- -grain-boundary interactions and identifies the deformation and slip transfer mechanisms. 3) SEM in-situ microcantilever beam bending test compares the fracture toughness of single grains dependent on irradiation and welding conditions. Date: Thursday, April 19, 2018 Time: 1:00 P.M. Place: ARMS 3115

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Seminar Notice for Daniel Kim's Ph.D. Final. Seminar, Friday, April 20, at 11:30, in ARMS 1103; Exam same day, at 12:30, in ARMS 2222. "Ultra Purification of Gallium by Zone Refining"
by Son, Rosemary E 18 Apr '18

18 Apr '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Ultra-Purification of Gallium by Zone Refining" By Daniel Kim Purdue MSE Ph.D. Final Exam Advisors: Professor David Johnson and Professor Kevin Trumble ABSTRACT High electron mobility is essential to improve two-dimensional electron gas (2DEG) quality in MBE grown AlGaAs/GaAs heterostrucutures. Recently, gallium purity was identified as limit to electron mobility in such structures. A laboratory horizontal zone refiner was constructed and procedures such as cleaning operation and handling/extracting samples were developed to suit needs for producing ultra-high purity gallium. One major problem is that the most of impurities are already below detection limit of current measurement techniques for starting high purity gallium. The 8N gallium (99.999999%, 10 ppb nominal purity) is the most commercially available pure gallium and measuring exact concentration becomes more difficult to determine the purity after zone refining. Thus, a last zone back-calculating approach was developed to characterize and to quantify purity in the purified zone. First, the performance of the zone refiner was evaluated using 5N gallium, intentionally doped with 14 different impurities (Cd, In, Sn, Ni, Cu, Zn, Pb, Bi, Ge, Au, Mn, S, Co, Al). Methods of measuring the effective partition coeffcients(keff) values for the first and the last zone were tested. All elements had keff values less than unity, but the values were increased as number of pass increased from n=1 to n=5 for the purified zone and n=5 for the last zone. The keff values assumed to be the same regardless of number of passes, but the zone length stability was a key factor affecting the keff values. One of the promising results from the 5N gallium study is that Mg and Sb having C0 below GDMS detection limit of 0.1 and 0.5 ppb were sufficiently raised to a useful detection limit of 20 and 1 ppb in the last zone. The last zone approach used in 5N gallium study was applied to the 8N gallium experiments and the purity in the first zone was back-calculated to estimate the overall purity. For the 1st 8N gallium experiment, the starting purity of >7N6 Ga was estimated to be >9N2 Ga based on 16 different elements after ten passes, whereas the starting purity of >7N4 was estimated to be >8N5 after nine passes for the 2nd 8N gallium experiment. However, C0 variations for In and Zn were determined from contamination and purity control studies. The C0,In varied from 120 to 0.3 ppb and from 10 to <0.5 ppb for Zn. Thus, there can be possible errors in estimating the purity for In and Zn when high C0 ingots are placed in the front zone. The expected In concentration in the purified zone was much less than below GDMS detection limit of 0.1 ppb, but the measured concentration showed 15 ppb for the 1st experiment. The same trend was observed for the Zn in the 2nd experiment. The measured concentration was 21 ppb, but the expected concentration was much less than detection limit of 0.5 ppb. Thus, recommendations for future experiment must be provided to overcome the C0 variation problems. Assuming that high C0 value of 500 ppb for In and Zn are located in the first 10 cm zone, the required number of passes to reach below detection limit is 24 for In and 20 for Zn. Practical number of passes is between 30 and 50 passes, which the starting purity of 6N gallium is expected to be purified to beyond the 10N gallium purity. Date: Friday, April 20, 2018 Time: 11:30 A.M. PURDUE MSE [cid:image002.png@01D3D6F1.C47CEC20] Place: ARMS 1103

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Seminar Reminder for David M. Guzman's Ph.D. Final. Seminar: Wednesday, April 18, in ARMS 1109, at 1:00; Exam same day, in ARmS 2009 at 2:00. " Structural, Thermodynamic, Electronic Properties of Mixed Ionic/Electronic Conductor Materials"
by Son, Rosemary E 17 Apr '18

17 Apr '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Structural, Thermodynamic, and Electronic Properties of Mixed Ionic-Electronic Conductor Materials" By David M. Guzman Purdue MSE PhD Final Exam Advisor: Professor Alejandro Strachan ABSTRACT Resistive switching electronic devices based on electrochemical metallization (ECM) cells are promising candidates from many beyond-CMOS applications. With the aim of unraveling the physics behind filamentary and threshold switching in ECM cells consisting of solid mixed ionic-electronic conductor electrolytes, this work focused on using first-principles calculations to characterize the structural, thermodynamic, and electronic properties of copper-doped amorphous silicon dioxide and copper-doped germanium-based glassy chalcogenides. The morphology and diffusion of small copper clusters embedded in amorphous silicon dioxide were characterized by density functional theory calculations. The average formation energy of a single copper ion in the amorphous matrix is found to be 2.4 eV. The theoretical predictions show that copper clusters with an equiaxed morphology are always energetically favorable relative to the dissolved copper ions in a-SiO2. Threshold conduction is predicted to be the transport mechanism for glassy sulfides and selenides due to the ability of copper to remain dissolved in the amorphous matrix even at high metal concentration. Furthermore, the charge carrier transport in sulfur and selenium glasses was found to be assisted by defective states derived from chalcogen atoms whose bonds exhibit a polar character. Date: Wednesday, April 18, 2018 Time: 1:00 P.M. Place: ARMS 1109

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FW: A Special Seminar : Professor Grethe Winther, Technical University of Denmark
by Son, Rosemary E 17 Apr '18

17 Apr '18

Dear All Colleagues wanting to meet with Grethe please feel free to let me know. Title: Coupled experiment and modelling to study grain orientation and interaction effects in deformed metals Date: TODAY Time: 10:30 am Coffee/Pastry; 11:00 am Seminar starts Place: ARMS 1103 Thank you, Anter El-Azab - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Anter El-Azab, Professor School of Materials Engineering Purdue University Editor-in-Chief, Materials Theory (Springer-Nature Group) Neil Armstrong Hall of Engineering 701 West Stadium Avenue West Lafayette, IN 47907-2045 Phone: 765-496-6864 Fax: 765-494-1204 E-mail address: aelazab(a)purdue.edu<mailto:aelazab@purdue.edu>

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