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Summer 2008 Seminar
Monday, July 7 at 3:30 p.m., Room 184 Watts Hall
Ryan Dehoff
PhD Candidate advised by Drs. Michel Mills & Hamish Fraser
Department of Materials Science and Engineering
The Ohio State University
Microstructure and Properties of LENS™ Deposited Nb-Ti-Si and Nb-Ti-Si Based Alloys
Abstract
Ni-based superalloys used in the hot section of turbine engines are currently being pushed to their limit in terms of high temperature performance. With the ever increasing elevated temperature demands placed on airplane turbine engines comes the need for the development of new alloys capable of withstanding these harsh environments. Niobium silicide based materials show promising potential to meet the temperature demands of the future. The system is based on the Si lean portion of the binary Nb-Si phase diagram. In this region, two different monolithic silicides form, Nb3Si and Nb5Si3, which possess high strengths and melting temperatures but are also very brittle. The overall toughness of the system is increased by incorporating the silicides in a ductile niobium phase to create a metal matrix composite.
The current research uses laser engineered net-shaping or LENS™ processing to deposit several different compositions of Nb-Si based alloys. There are several benefits to using LENS™ processing including fast cooling rates that can significantly refine the microstructure. The processing parameters were optimized to yield quality depositions and the resulting microstructures were examined. The high temperature oxidation behavior and high temperature compression behavior of the various alloys and microstructures were tested.
Bio
Ryan was raised in Lancaster, Pa and came to The Ohio State University after graduating high school in 1997. He completed his undergraduate degree in 2002 from OSU at which point he returned to Ohio State to pursue his graduate degree under the guidance of Dr. Mike Mills. He has been co-advised by H. Fraser and J. Williams while working on a NASA/DOD project on Niobium Silicide based alloys. In his free time, Ryan is and avid rock climber and enjoys the outdoors, spending time with his dog, and participating in various sports.
