WE Colloquium: Rajiv Mishra, Exceptional properties by expanding microstructural landscape via friction stir processing

Center for Friction Stir Processing, Dept of Materials Science and Engineering, Un of North Texas

Abstract

High performance structural alloys have complex interplay of chemistry and microstructural features. The dominant mechanisms can be changed by altering grain size, precipitate size and morphology, and texture. These are intertwined with alloy chemistry and processing. In the last decade, friction stir processing (FSP) has been developed as a generic technique for microstructural modification. In this talk, examples of exceptional properties obtained by FSP will be given. For magnesium alloys, FSP can produce a wide range of microstructures, from highly textured microstructure to a random texture with large fraction of high angle grain boundaries. Ultrafine grained magnesium alloys can be produced by controlling the peak process temperature. Intense shear deformation during FSP at high temperature leads to dissolution of constituent particles in high strength magnesium alloys like WE43. Model microstructural conditions have been developed via FSP and used to investigate deformation micromechanisms. Other examples will include an Al-Ti-Cu alloys with >700 MPa strength and >10% ductility, and a Ti6246 alloy with ~2GPa strength and >5% ductility. All these examples of lightweight alloys with very high strength-ductility combinations are rooted in microstructural space not available by conventional thermo-mechanical processing routes.

Bio

Rajiv Mishra (Ph.D. in Metallurgy from the University of Sheffield) is a Distinguished Research Professor at the University of North Texas. He serves as the Director of a recently launched Advanced Materials and Manufacturing Processes Institute (AMMPI) at UNT. He is also the UNT Site Director of the NSF I/UCRC for Friction Stir Processing and a Fellow of ASM International. He is a past-chair of the Structural Materials Division of TMS and served on the TMS Board of Directors (2013-16). He has authored/co-authored 285 papers in peer-reviewed journals and proceedings and is principal inventor of four U.S. patents. His current publication based h-index is 43 and his papers have been cited more than 9000 times. He has co-authored a book on friction stir welding and processing, and edited or co-edited twelve TMS conference proceedings. He serves on the editorial board of Materials Science and Engineering A and Science and Technology of Welding and Joining. He is the founding editor of a short book series on Friction Stir Welding and Processing published by Elsevier and has co-authored five short books in this series.