Martensite Transformation Intergrain and Intragrain Autocatalysis in Fe-Ni alloys

This work presents a consolidated view of the autocatalysis, thermal and entropic effects in martensitic transformation of polycrystalline Fe-31wt%Ni-0.02wt%C, which has been a standard material for the investigation of fundamental aspects of the martensite transformation. The present work is based...

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Bibliographic Details
Published in:Materials research (São Carlos, São Paulo, Brazil) São Paulo, Brazil), 2017-11, Vol.20 (6), p.1548-1553
Main Authors: Guimarães, José Roberto Costa, Rios, Paulo Rangel
Format: Article
Language:English
Subjects:
Autocatalysis
ENGINEERING, CHEMICAL
Ferrous alloys
iron-nickel alloys
Martensite
martensite transformation
Martensitic transformations
MATERIALS SCIENCE, MULTIDISCIPLINARY
METALLURGY & METALLURGICAL ENGINEERING
metals and alloys
microstructure
Nucleation
Temperature dependence
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Summary:This work presents a consolidated view of the autocatalysis, thermal and entropic effects in martensitic transformation of polycrystalline Fe-31wt%Ni-0.02wt%C, which has been a standard material for the investigation of fundamental aspects of the martensite transformation. The present work is based on the description of classical microstructure descriptors of the transformation and on generally accepted concepts regarding the martensitic transformation in iron base alloys. Present work agrees with the view that the autocatalysis is a means by which the martensite transformation promotes further nucleation and growth. Autocatalysis induces the nucleation and growth of secondary plates in addition to the relatively small number of primary nucleation sites and their corresponding primary plates. We demonstrate that autocatalysis can be factored out into intragrain and intergrain components. The analysis of these factors establishes that intragrain autocatalysis is athermal but intergrain autocatalysis possess an Arrhenius temperature dependence. The reasons for such a behavior are discussed in detail.
ISSN:1516-1439
1980-5373
1980-5373
DOI:10.1590/1980-5373-mr-2016-0880