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SUMMARY:Theoretical Modeling of High Entropy Alloys
DTSTART;VALUE=DATE-TIME:20210730T093000Z
DTEND;VALUE=DATE-TIME:20210730T094500Z
DTSTAMP;VALUE=DATE-TIME:20260415T201824Z
UID:indico-contribution-7067@events.saip.org.za
DESCRIPTION:Speakers: Volkmar Nolting (Vaal University of Technology)\nHig
 h entropy alloys (HEA) containing Co\, Ni\, Fe have recently enjoyed consi
 derable attention in the material sciences due to their interesting mechan
 ical and magnetic properties that are further enhanced by the additive man
 ufacturing technique often used to process them.\nHEAs are theoretically d
 ifficult to describe as they often form amorphous structures and the Bloch
  theorem is not applicable. In this article the method of the effective me
 dium is used and the corresponding many body problem is solved selfconsist
 ently within the coherent potential approximation. The mixing entropy of H
 EAs and their phase stability are explained using an optimization approach
 . The complex micro- and multi phase structure are due to many body effect
 s that are discussed from a calculation of the quasiparticle density of st
 ates. It turns out that these many body effects are most significant if th
 e components of the alloy are present at about equal proportions. Applicat
 ions to Kondo insulators and superparamagnetism are investigated where the
  interaction between magnetic moments is of indirect type and mediated by 
 the free electrons of the conduction band (RKKY interaction). In the stron
 g coupling limit it is shown that the susceptibility has a maximum at the 
 blocking temperature indicating a phase transition from ferromagnetism to 
 superparamagnetism. Using alternatively a lattice gas model to represent t
 he disordered alloy the existence of the second order phase transition is 
 confirmed and the blocking temperature is calculated. It is shown that the
  results of the two model calculations are in qualitative agreement with o
 ne another and must thus be regarded as good and reliable.\n\nhttps://even
 ts.saip.org.za/event/206/contributions/7067/
LOCATION:North-West University Potchefstroom Campus
URL:https://events.saip.org.za/event/206/contributions/7067/
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