Day: September 5, 2008

Processing and Properties of Amorphous Reinforced Crystalline Matrix Composites in Ni-W Alloy System

Friday, September 5, 2008 3:00 – 4:00 pm
Room 610, M&M Building

Alex O. Aning
Virginia Polytechnic Institute & State University
Department of Materials Science & Engineering
Blacksburg, Virginia 24061

Abstract

Metal Matrix Composites (MMCs) are used as structural materials because of their ability tohave a combination of high strength and good ductility.  A common problem with MMCs utilizingvastly different materials is the difficulty in forming a strong matrix/reinforcement interfacewithout suffering extensive dissolution, debonding, or chemical reactions between thecomponents.  By using a reinforcement which has a similar chemistry and local atomic structureto that of the matrix, these critical problems can be reduced.  In this work, a nickel baseamorphous particulate reinforced crystalline nickel matrix composites were processed.  Thereinforcement, an equimolar NiW amorphous powder, was synthesized in a SPEX mill by themechanical alloying process.  The amorphous and crystalline nickel powders were blended inan Attritor mill in varying volume fractions and then consolidated using: hot-isostatic pressing(HIP), or combustion driven compaction (CDC) process.  This work revealed that the amorphousNiW reinforcement provided strength and hardness to the ductile Ni matrix while simultaneouslymaintaining a strong interfacial bond due to the similar chemistry of the two components.  Thestrengthening achieved in the composite is attributed to particulate/matrix boundary strengthening.

Biography

Dr. Alex O. Aning is an Associate Professor of Materials Science and Engineeringat Virginia Tech.  He obtained the BS degree in Physics from Morgan State University,Baltimore in 1977, and Ph.D. in Metallurgical Engineering from University of Missouri- Rolla in1982.  After a year of post-doctoral studies at Rolla he joined the Physics Department at MorganState in 1983.  At Morgan State he helped develop a new engineering school.  He later becamethe head the Electrical Engineering Department and lead it to become ABET accredited on thefirst attempt.  He joined Virginia Tech in 1992; from 1998 to 2005, he was part of theEngineering Education Department.  He has held visiting professorships at the Johns HopkinsUniversity (1992) and the University of Virginia (1989/90).  He does research in the areas ofphase transformations, and synthesis and processing of metallic, ceramic and compositematerials.  His current activities include solid-state formation of bulk amorphous alloys, andamorphous phase-strengthened metal matrix composites.  He is a member of TMS and ASMInternational.