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dc.contributor.advisorMcNelley, Terry R.
dc.contributor.authorCuevas, Assunta Mariela.
dc.dateSeptember 2002
dc.date.accessioned2012-03-14T17:37:02Z
dc.date.available2012-03-14T17:37:02Z
dc.date.issued2002-09
dc.identifier.urihttp://hdl.handle.net/10945/3027
dc.descriptionApproved for public release, distribution is unlimiteden_US
dc.description.abstractThe effect of friction-stir processing (FSP) on the microstructure of a cast nickel-aluminum bronze (NAB) material has been characterized by various micro-analytical methods including orientation imaging microscopy (OIM). Cast NAB is widely utilized in the production of propellers for the surface ships and submarines of the U.S. Navy due to excellent corrosion-resistance. New applications require improved mechanical properties that may be attainable using FSP to achieve localized microstructure modification. Friction between a rotating tool and the surface of the material results in a *stirring* action that, in turn, produces adiabatic heating and local softening of the material. The tool rotation results in very large shear deformations in the softened regions and thus microstructure refinement and homogenization; in effect FSP may convert an as-cast microstructure to a wrought condition in the absence of macroscopic shape change. In as-cast material, results of optical and scanning electron microscopy (using energy dispersive analysis) show an ` (FCC) matrix containing globular and particulate dispersions that correspond to the *I, *II and *IV second phases; these represent various morphologies of the Fe3Al intermetallic compound, which has a D03 structure. Also present are lamellar particles of *III, which is NiAl and has a B2 structure. The grain size in the ` matrix is ~ 1 mm. In OIM, the microtexture and microstructure in the ` (FCC) matrix may be readily obtained and analyzed. However, interatom distances in the Fe3Al and NiAl phases differ by only about one percent and so these phases are not distinguishable from one another during OIM. Altogether, microstructure and microtexture analysis showed that there are several regions in the thermomechanically affected zone (TMAZ) of a material subjected to FSP. From base material inward toward the TMAZ, these include: annealing effects in undeformed base material; a region just inside the TMAZ in which grain deformation and C-type shear deformation textures are observed; regions of highly refined and recrystallized grains further inside the TMAZ, wherein the grain size is < 5æm; and, finally, regions of elongated, banded and twinned grain structures that suggest grain growth following recrystalliztion.en_US
dc.description.urihttp://archive.org/details/microstructurech109453027
dc.format.extentxvi, 57 p. : ill. (some col.) ;en_US
dc.publisherMonterey, California. Naval Postgraduate Schoolen_US
dc.rightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, may not be copyrighted.en_US
dc.subject.lcshFrictionen_US
dc.subject.lcshNickel-aluminum alloysen_US
dc.subject.lcshMicroscopyen_US
dc.titleMicrostructure characterization of friction-stir processed nickel-aluminum bronze through orientation imaging microscopyen_US
dc.typeThesisen_US
dc.contributor.departmentMechanical Engineering
dc.subject.authorNickel aluminum bronzeen_US
dc.subject.authorFriction stir processingen_US
dc.subject.authorOrientation imaging microscopyen_US
dc.subject.authorElectron backscatter diffractionen_US
dc.subject.authorEnergy dispersive spectroscopyen_US
dc.subject.authorOptical microscopyen_US
dc.subject.authorThermomechanically-affected zoneen_US
dc.subject.authorShear deformationen_US
dc.description.serviceLieutenant, United States Navyen_US
etd.thesisdegree.nameM.S. in Mechanical Engineeringen_US
etd.thesisdegree.levelMastersen_US
etd.thesisdegree.disciplineMechanical Engineeringen_US
etd.thesisdegree.grantorNaval Postgraduate Schoolen_US
etd.verifiednoen_US


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