MSE PhD Seminars I

All talks will be held in 184 Watts Hall

9:00 a.m. Daniel Huber advised by Dr. Hamish Fraser

A Combinatorial Approach for the Study of Low Modulus Alloys Titanium Alloys

Abstract:

Developments in Titanium-Tantalum alloy system, with lower elastic modulus than traditional Ti-6Al-4V and better bio-compatibility, could benefit implant applications. Alloy system samples of graded composition were produced by Optomec LENS 3D printing technology. LENS samples were produced from a blend of elemental powders.  Alloy ingots were also prepared by traditional vacuum arc melting. The role of Oxygen as a modifier of the elastic modulus in the context of an impurity as well as an alloy addition will be discussed.  A brief discussion of the benefits and limitations to the combinatorial methods applied will be included.  Microstructural investigations were performed by DualBeam™ FIB, STEM and TEM techniques. The elastic modulus of small specimens  was measured by instrumented indentation and compared to measurements made by ultra sonic methods.

Bio:

Daniel currently works as a instrumentation scientist at the Center for Electron Microscopy and Analysis (CEMAS). Daniel also directly oversees two Dual BeamTM Focused Ion Beam (FIB) instruments. First an FEI Helios NanoLab™ 600 and a FEI Nova NanoLab™ 600. Prior to working at CEMAS he has worked as a Research Engineer at CAMM since 2007. His primary research interest is the characterization of Titanium phase transformations, microstructure and morphologies.  Daniel seeks to better understand the microstructure and property relationships in titanium alloys.

10:00 a.m. Samuel Kuhr advised by Dr. Hamish Fraser

Mechanical Properties and Characterization of Microstructural Gradients with Various Gamma Prime Distributions in Low Solvus High Refractory (LSHR) Nickel Superalloy

Abstract:

Hybrid turbine disks are designed to improve resistance against a range of failure modes with spatial variations in microstructure to enhance site-specific properties.  An LSHR nickel base superalloy turbine disk was processed with a dual microstructure heat treatment (DMHT) that produces a gradient in grain and gamma prime size from the bore to the rim. In this investigation, transition region was investigated to understand how various gamma prime size and distribution affect its mechanical properties.   As-received as well as solution treated and aged (STA) microstructural gradients were tensile tested at room temperature.  HR-SEM was used to characterize the various gamma prime sizes and distribution after each STA sequence.  Tensile testing was performed in conjunction with digital image correlation (DIC) to determine bulk and localized strains.  The natures of the deformation substructures were examined by TEM and any correlation between microstructure and mechanical properties has been assessed and will be presented.

Bio:

Mr. Samuel Kuhr received a B.S. in Chemical Engineering (2001) and M.S. in Materials Engineering (2003) from the University of Dayton.  He pursued research in nondestructive testing at Wright Patterson Air Force Base until 2009, upon which he left WPAFB to pursue his Ph.D. at The Ohio State University in Materials Science and Engineering.  From 2009 to the present, Samuel works at the Center for the Accelerated Maturation of Materials for his advisor, Dr. Hamish Fraser on the characterization of nickel superalloys.

2:00 p.m. Zhiyuan Niu advised by Drs. Sheikh Akbar and Suliman Dregia 

Nanoscale Self-patterning and Engineering of YSZ surfaces

Abstract:

This dissertation aims to develop a cost-efficient surface patterning technique based on a strain mediated self-assembly in rare earth oxide (REO)/yittria-stabilized zirconia (YSZ) systems. Powder based techniques were developed to disperse the REO while the growth kinetics of the nanostructures were systematically studied. It was further discovered that ordered step arrays can be produced on two different types miscut YSZ substrates via substrate pre-annealing. These steps are subsequently used as templates to guide the self-assembly, which results in significantly improved alignment of the nanostructures.  The effects of annealing gas environment were also explored and discussed.

Bio:

Zhiyuan Niu received his B.S. degree (2012) in Materials Science and Engineering from Tsinghua University, China. He is currently a Ph.D. candidate in the Department of Materials Science and Engineering at the Ohio State University, USA. His research focuses on surface patterning, nanostructure fabrication and self-assembly phenomena in ceramic systems.

Format and attendance

The Department will hold all of our SP16 PhD talks (eleven) over the course of two days, April 20 & 21. The talks will be held in 184 Watts Hall, not 264 MacQuigg.

MSE grad students will be required to attend at least two of the eleven talks presented over the course of 4/20 & 21. Attendance will be taken and if a student has attended two seminars total over the course of the two days, s/he will receive a passing grade for this part of 7895. Attendance is limited to the number of seats in the room.