Paper Title:
Microstrain Analysis of Titanium Aluminides
  Abstract

The aeronautic and automotive industries have shown a renewed interest in TiAl based alloys. The main reasons for such an interest are their low density (~3,8g/cm3), a good stiffness and a high strength for temperatures up to 750°C. However, these alloys exhibit, in their polycrystalline form, a poor ductility at room temperature with widely scattered values. The aim of this study is therefore to characterise their mechanical behaviour with a multiscale methodology, coupling microstructure analysis and strain field measurements. This methodology employs orientation imaging microscopy as well as digital imaging correlation techniques with an intragranular step size of a few micrometers. Two chemical compositions (47 at. % Al and 48 at. % Al) and two processing routes (casting and powder metallurgy) are studied. Thus, four different types of final microstructures are considered, from fully lamellar Ti3Al (a2) + TiAl (g) microstructure to bimodal ones composed of two-phase (a2+g) lamellar grains and monolithic g grains. Firstly, the microstructure is characterised crystallographically and morphologically. This allows the identification of a representative volume element (RVE) inside the analysed volume. Then, uniaxial mechanical tests are performed for each microstructure, and the strain fields are analysed with a multiscale approach, which determines the spatial distribution of the strain field heterogeneity with respect to the different microstructures.

  Info
Periodical
Materials Science Forum (Volumes 638-642)
Main Theme
Edited by
T. Chandra, N. Wanderka, W. Reimers , M. Ionescu
Pages
1330-1335
DOI
10.4028/www.scientific.net/MSF.638-642.1330
Citation
E. Héripré, D. Caldemaison, A. Roos, J. Crépin, "Microstrain Analysis of Titanium Aluminides", Materials Science Forum, Vols. 638-642, pp. 1330-1335, 2010
Online since
January 2010
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$32.00
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