Texture, microstructure et propriétés d'un alliage Fe-40AI à grains fins obtenus par métallurgie des poudres et extrusion : influence des paramètres du procédé et de traitements thermiques

Abstract : The elaboration of B2 structured Fe 40 %at. Al intermettalics by mechanical alloying, reinforced by a fine dispersion of yttrium oxides, have blast a way to overcome the problems due to their brittleness and poor ductility. This study deals with the characterization of the influence of parameters of the elaboration process on the evolution of the microstructures, the textures and the mechanical properties of extruded bars. In order to analyse this evolutions, the extrusion ratio and temperature were modified. Powders of different nature were also used and the effect of heat treatments were investigated as well. The microstructure have been characterized by TEM, the textures have been measured by X ray diffraction, by EBSP and by OIM. Tensile tests were carried out to determine the mechanical properties. The analysis of the formation of textures have been completed by simulations with the help of the Taylor model and the anisotropy have been characterized by using models of Reuss, Voigt and Hill. The increase of the extrusion temperature reinforces first the deformation texture characterized by a <110> fibre. At 1250°C, the <110> fibre texture is partly replaced by a <111> fibre related with recrystallization. The fact that deformation texture is retained up to 1200°C is due to the fine oxide dispersion inhibiting the recrystallization. In terms of stiffness, the appearance of the <111> fibre is counterbalanced by the weakening of the <110> component. The influence of the microstructure on the yield strength could be rationalized by considering the hardening due to the grain and the oxide particles sizes as well as the hardening due to the presence of matrix defects. The heat treatments showed that above a temperature, identified to be B2 ? A2 phase transition temperature (near 1270°C), abnormal growth of <111> oriented grains takes place without primary recystallization.Bellow this critical temperature the microstructure remains very stable
Document type :
Theses
Complete list of metadatas

Cited literature [6 references]  Display  Hide  Download

https://hal.univ-lorraine.fr/tel-01748960
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 11:55:41 AM
Last modification on : Monday, April 16, 2018 - 10:43:11 AM
Long-term archiving on : Friday, September 14, 2018 - 9:30:43 AM

File

Lenhard.Sebastien.SMZ0128.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01748960, version 1

Collections

Citation

Sébastien Lenhard. Texture, microstructure et propriétés d'un alliage Fe-40AI à grains fins obtenus par métallurgie des poudres et extrusion : influence des paramètres du procédé et de traitements thermiques. Autre. Université Paul Verlaine - Metz, 2001. Français. ⟨NNT : 2001METZ028S⟩. ⟨tel-01748960⟩

Share

Metrics

Record views

38

Files downloads

14