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SUMMARY:Exploding\, weeping and reversible phase transformations in cerami
 cs - Prof Richard James\, Distinguished McKnight University Professor\, De
 partment of Aerospace and Engineering Mechanics\, University of Minnesota
DTSTART:20220211T140000Z
DTEND:20220211T150000Z
UID:TALK169721@talks.cam.ac.uk
CONTACT:46601
DESCRIPTION:The systematic tuning of the lattice parameters to achieve imp
 roved kinematic compatibility between phases is a broadly effective strate
 gy \nfor improving the reversibility\, and lowering the hysteresis\, of so
 lid-solid phase transformations.  Thus\, it came as a big surprise\, in jo
 int work with \nEckhard Quandt and his group in Kiel\, that our attempt to
  use these methods to guide the search for a shape memory ceramic led not 
 to a high \ndegree of reversibility\, but rather to violently explosive or
  “weeping” behavior (i.e.\, gradual falling apart at the grain boundar
 ies) in oxides of ZrHfYNb. \nIn the lecture I will review the theory of su
 percompatibility and its applications\, and then turn to the puzzle of ZrH
 fYNb.  Several aspects of this \nsystem are unusual -- multiple transforma
 tion correspondences (also seen in TiNi) and unusual symmetries – and we
  analyze the behavior in \nlight of these features.  Overall\, our results
  show a diversity of behavior\, from reversible to explosive\, is possible
  in a chemically homogeneous \nsystem by slight manipulation of conditions
  of compatibility.\n
LOCATION:Zoom Meeting ID: 898 3752 1667
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