Microstructural modification of as-cast NiAl bronze by friction stir processing
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Authors
Oh-Ishi, Keiichiro
McNelley, Terry R.
Subjects
Advisors
Date of Issue
2004-09
Date
Publisher
Language
Abstract
The application of friction stir processing (FSP) to a cast NiAl bronze (NAB) material is presented
as a means for selective modification of the near-surface layers by converting as-cast
microstructures to a wrought condition in the absence of macroscopic shape change. This may enable
selective surface hardening of cast components. The complex physical metallurgy of the NAB is
reviewed, and microstructure changes associated with FSP for a selected set of processing
parameters are examined by optical microscopy (OM) and transmission electron microscopy (TEM)
methods. Direct temperature measurement in the stir zone is infeasible and, so, these
microstructure changes are used to estimate peak temperatures in the stir zone. The persistence of
a Fe3Al phase (Kii) indicates that peak temperatures are below the solvus for this phase, while the
presence of transformation products of the f3 phase, including fine Widmanstätten a., bainite, and
martensite, indicates that peak temperatures exceed the eutectoid temperature for the reaction
β →ᵅ + Kiii throughout the stir zone.
Type
Article
Description
Series/Report No
Department
Mechanical and Astronautical Engineering
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Defense Advanced Research Projects Agency (DARPA)
Funder
Format
11 p.
Citation
K. Oh-Ishi, T.R. McNelley, "Microstructural modification of as-cast NiAl bronze by friction stir processing," Metallurgical and Materials Transactions A, v.35A, (September 2004), pp. 2951-2961.
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.