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Title: Preferential nucleation during polymorphic transformations

Polymorphism is the ability of a solid material to exist in more than one phase or crystal structure. Polymorphism may occur in metals, alloys, ceramics, minerals, polymers, and pharmaceutical substances. Unresolved are the conditions for preferential nucleation during polymorphic transformations in which structural relationships or special crystallographic orientation relationships (OR’s) form between the nucleus and surrounding matrix grains. We measured in-situ and simultaneously the nucleation rates of grains that have zero, one, two, three and four special OR’s with the surrounding parent grains. These experiments show a trend in which the activation energy for nucleation becomes smaller – and therefore nucleation more probable - with increasing number of special OR’s. As a result, these insights contribute to steering the processing of polymorphic materials with tailored properties, since preferential nucleation affects which crystal structure forms, the average grain size and texture of the material, and thereby - to a large extent - the final properties of the material.
Authors:
 [1] ;  [2] ;  [2]
  1. Delft Univ. of Technology, Mekelweg (Netherlands); Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Delft Univ. of Technology, Mekelweg (Netherlands)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Netherlands Organisation for Scientific Research (NWO); USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; metals and alloys; pharmaceutics; solid-state chemistry; structural geology
OSTI Identifier:
1340284