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SUMMARY:IMX Seminar Series - Predicting deformation behaviour in structura
 l alloys with electronic structure calculations
DTSTART:20231016T131500
DTEND:20231016T141500
DTSTAMP:20260414T171501Z
UID:14387ac30339089a655cb58a8cea215627e25383abe5153948142235
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Michael S. Titus\, Purdue University\, USA\nNi-based sup
 eralloys can exhibit a wide range of deformation behavior depending on all
 oy composition\, microstructure\, temperature\, strain rates\, and applied
  stresses. Characterizing the deformation behavior often requires time con
 suming and potentially expensive experiments\, but new models and increase
 d computational power combined with density functional theory have enabled
  electronic structure calculations to predict deformation behavior in Ni-b
 ased superalloys and other structural alloys. In the first example in this
  presentation\, our attempts to model solute segregation behavior to plana
 r defects during deformation\, known as Suzuki Segregation\, will be shown
 . In this work\, we utilized a combination of cluster expansion and Monte 
 Carlo techniques housed within the a Clusters Approach to Statistical Mech
 anics (CASM) software to determine equilibrium concentrations of solute in
  Co-Ni disordered FCC alloys and Ni3Al-based ordered alloys [1]. We extend
 ed this work to investigate the segregation tendency across all Ni-X and C
 o-X transition metal binaries and uncovered the complex interactions that 
 are responsible for controlling segregation or depletion tendencies to sta
 cking faults in these alloys. Recent experimental validation of these pred
 ictions will also be presented. In the second example\, we show how calcul
 ation of the generalized stacking fault energy (GSFE) surface can be used 
 to predict deformation in a novel -Ni2(Cr\,Mo\,W)-strengthened superalloy\
 , Haynes® 244®. Owing to its lower symmetry\, the phase presents itself 
 as 6 different orientation variants coherently embedded in the disordered 
 FCC matrix and exhibits two close-packed planes and three unique deformati
 on pathways. We show that the combination of these characteristics leads t
 o the formation of microtwins at temperatures and strain rates ranging fro
 m 23 – 760 ºC and 10-3 –\n10-9 s-1\, respectively [2]. These results 
 suggest that new structural alloys could be designed with unique precipita
 tes that enable favorable deformation mechanisms for improved ductility an
 d work hardening over a wide range of temperatures.\n[1] Wen\, D.\, & Titu
 s\, M. S. (2021). First-principles study of Suzuki segregation at stacking
  faults indisordered face-centered cubic Co-Ni alloys. Acta Materialia\, 2
 21\, 117358. [doi]\n[2] Mann\, T.\, Fahrmann\, M. G.\, & Titus\, M. S. (20
 22). Ab Initio Investigation of Planar Defects inImmm-Ni2 (Cr\, Mo\, W) St
 rengthened HAYNES 244 Alloy. Metallurgical and Materials Transactions A\,5
 3(12)\, 4188-4206. [doi]\nhttps://engineering.purdue.edu/MSE/people/ptProf
 ile?resource_id=144082\n\nBio: Prof. Michael Titus is a tenured Associate 
 Professor and Technical Director of the Purdue Heat Treating Consortium at
  the School of Materials Engineering at Purdue University in West Lafayett
 e\, IN\, USA. Prior to joining Purdue University in 2016\, he earned his B
 .S. in Engineering Physics at The Ohio State University\, 2010 and Ph.D. i
 n Materials at the University of California Santa Barbara\, 2015. From 201
 5 to 2016 he was an Alexander von Humboldt Postdoctoral Fellow at the Max 
 Planck Institute for Iron Research in Dusseldorf\, Germany. Prof. Titus Pr
 of. Titus is the recipient of the NSF CAREER award (2018) and many profess
 ional society awards including the TMS SMD Young Leaders Professional Deve
 lopment Award (2017)\, TMS-JIM Young Leaders International Scholar\n(2020)
 \, and the ASM Bradley-Stoughton Award for Young Teachers (2021). He has c
 o-authored over 35 peer-reviewed publications\, has supervised 10 Ph.D. an
 d Masters thesis students\, and is currently advising 7 Ph.D. students
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
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