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Materials Science and Engineering Seminar

Joshua Mueller

Assistant Professor, Materials Science and Engineering
Michigan Technological University

Abstract

Multi-phase ferrous alloys have duplex microstructures consisting of face-centered-cubic austenite (referred to as retained austenite) and body-centered-cubic ferrite or a ferrite-based constituent (martensite or bainite). To generate these microstructures, austenite-stabilizing alloy additions are required, typically manganese (Mn) and/or nickel (Ni). The alloy is partitioned during thermal processing, enriching the austenite with the stabilizing solute and enabling austenite retention upon cooling. These duplex microstructures are associated with increased combined strength and toughness; however, the mechanical performance is sensitive to relatively minor changes in alloy and heat treatment. The austenite composition, and corresponding deformation mechanism, is believed to have a crucial influence on the mechanical flow behavior of these alloys. Therefore, there is considerable interest in developing confident correlations between austenite characteristics and mechanical performance. The research outlined here is aimed at (1) elucidating the effect of austenite deformation mechanisms on the flow behavior in duplex microstructures and (2) understanding kinetic transitions with respect to partitioning and non-partitioning phase transformation mechanisms. Results aim to guide alloy and heat treatment design using advanced thermal processing techniques to generate duplex microstructures with increased performance.

Bio

Mueller is an assistant professor in the Department of Materials Science and Engineering at Michigan Technological University, where he teaches courses relating to thermodynamics of materials, phase transformations and microstructure-mechanical property relationships. He also holds a guest scientist appointment with the Dynamic Structure Design & Engineering and Vessel Operations Group at Los Alamos National Laboratory.

Mueller earned a PhD in Metallurgical and Materials Engineering from the Colorado School of Mines through the Advanced Steel Processing and Products Research Center, and a BS in Materials Science and Engineering from the University of Wisconsin-Madison. His broad research interests include fundamentals of phase transformations and microstructural evolution of materials as well as microstructure-mechanical property relationships. He is particularly interested in microstructural design to enhance yield strength-toughness performance of multi-phase ferrous alloys and incorporating thermodynamic and phase field simulations for an integrated computational materials engineering (ICME) approach to alloy and heat treatment development