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Closed Access item Superplastic Behavior of Hot Extruded Gamma TiAl (Mo, Si) Alloys

Authors:Jiménez, José Antonio
Carsí, Manuel
Ruano, Oscar Antonio
Frommeyer, G.
Knippscher, S.
Wittig, J.
Keywords:Creep, Extrusion, Microstructure, Superplasticity, Titanium aluminides
Issue Date:2003
Publisher:Trans Tech Publications
Citation:Materials Science Forum 426-432 : 1915-1920 (2003)
Abstract:Superplastic behavior of hot extruded intermelallic Ti-46Al-1.7(Mo,Si) (at%) alloys was studied by stress change tests in compression and tensile tests at temperatures ranging from 700 to 1050°C. The material produced by arc melting exhibited a structure of coarse lamellar grains in the as-cast condition that transforms to an equiaxic near γ microstructure after processing by hot extrusion at 1250°C. This microstructure consists of zones of γ grains finer than 1μm and band like regions with coarser grains, ranging from 5 to 20 μm. In addition to γ grains, a volume fraction of more than 20 vol% of α2-Ti3Al particles finely dispersed are also present in the fine-grained zones. Compression tests of the extruded material at stresses ranging from 4 to 825 MPa showed values of the strain-rate-sensitivity exponent near 0.5 at low stresses and/or high temperatures. The microstructure in the fine-grained areas remains essentially constant during deformation. TEM analysis of deformed samples in this regime leads to relate grain boundary sliding as the mechanism controlling the deformation process. High elongation to failure, characteristic of superplaslicity, was achieved at 975 and 1050°C at an initial strain rate of 4.6 × 10-4 and 4.6 × 10-3 s-1.
Publisher version (URL):http://dx.doi.org/10.4028/www.scientific.net/MSF.426-432.1915
URI:http://hdl.handle.net/10261/57395
ISSN:0255-5476
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Appears in Collections:(CENIM) Artículos

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