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学术讲座->学术讲座专家->Tresa M. Pollock

学术讲座专家—— Tresa M. Pollock

个人简介

Dr.Tresa M. Pollock is the L.H. and F.E. Van Vlack Professor of Materials Science and Engineering at the University of Michigan, Ann Arbor, MI. She graduated with a B.S. from Purdue University in 1984, and a Ph.D. from MIT in 1989. Dr. Pollock was employed at General Electric Aircraft Engines from 1989 to 1991, where she conducted research and development on high temperature alloys for aircraft turbine engines. She was a professor in the Department of Materials Science and Engineering at Carnegie Mellon University from 1991 to 1999. Dr. Pollock has received the ASM International Research Silver Medal Award, the Bradley Stoughton Award, the Carnegie Mellon Ladd Research Award and an NSF-NYI Award. She was elected to the National Academy of Engineering in 2005, is a Fellow of ASM International, Associate Editor of Metallurgical and Materials Transactions and was the 2005-2006 President of The Minerals, Metals and Materials Society.

学术讲座

High Temperature Mg-Al-Ca Based Alloys:Microstructure and Creep Behavior ——2008-06-13

Abstract:Improvements in fuel efficiency have motivated development of cast Mg-based alloys for automotive powertrain components that can operate in the temperature range of 150℃-250℃.Since Ca additions are promising, fundamental aspects of solidification, phase equilibrium and creep deformation mechanisms in Mg-Al-Ca systems have been investigated in permanent mold and die cast alloys. The development of cast microstructure, including segregation and the formation of intermetallics, has been investigated in AX44 (Mg-4Al-4Ca) and AXJ530 (Mg-5Al-3Ca-0.15Sr, wt%) alloys.Creep tests have been conducted over a stress/temperature range of 60 to 100 MPa and 125 to 175℃.A high temperature strain mapping technique has been employed to examine the creep deformation processes at the scale of the microstructure. Creep strains develop inhomogeneously at the grain scale and are not strongly influenced by grain boundary sliding or the interdendritic eutectic structure. ?The kinetics of precipitation of the Al2Ca (C15) phase and the effect of the precipitation on the creep strength has also been investigated.

Platinum Group Metal Modified Superalloys: Microstructures and High Temperature Properties ——2008-06-17

Abstract: Ni-based superalloys modified with platinum group metal (PGM) additions of Pt and/or Ir with selective amounts of Al, Cr, Re, Ta, and Hf have been investigated. Solidus, liquidus and solvus temperatures have been characterized over a wide range of composition.  Alloying resulted in precipitate morphologies ranging from cuboidal to spherical, with a strong influence of Cr, Re, Ta and Pt on morphology.  Compression creep tests were carried out in the range of 50-90 MPa at a constant 1000℃.  Directional coarsening behavior indicates that all PGM modified alloys have positive misfit with magnitudes ranging from 0.3-1.0%.  Creep tests further indicate that alloys containing (in at.%) 2.5% Pt or a combination of 2.5%Pt-2.5%Ir have higher resistance to creep deformation compared to alloys with 5%Pt or alloys containing only Ir.  The implications of these observations with respect to the design of high temperature bond coats or bulk superalloys for turbine airfoils will be discussed.