Skip to Main content Skip to Navigation
Theses

Comportement mécanique haute température du superalliage monocristallin AM1 : étude in situ par une nouvelle technique de diffraction en rayonnement synchrotron

Abstract : Nickel-based single crystal superalloys are extensively used for turbines blades (above 1000°C) of aeronautical engines because of their good thermomechanical properties. During stage II of creep, their microstructure consists of a γ matrix (fcc) and raft precipitates γ’ (L12). The aim of this work is to improve the understanding of plasticity of this type of alloy, especially the first generation AM1 superalloy. To follow his mechanical behaviour during fast transients, a new experimental setup using synchrotron radiation diffraction in transmission geometry was developed. A far field camera allows the recording of the (200) diffraction spot of each phase, i.e. the evolution of the lattice misfit in real time (one acquisition takes 7 seconds). By using a simple mechanical model, it is possible to determine the internal stresses and the plastic strains for both phases. An experimental campaign was performed at ID11 beamline of ESRF using this new technique. Two sample types with different initial microstructure (obtained with adapted heat treatments) were tested in situ. They underwent load jumps under high-temperature creep conditions. Further post mortem investigations by SEM and TEM were performed to determine their microstructure, to check on misorientations, map some elements composition and estimate the dislocation density within the γ’ rafts. In the γ channels, dislocation propagation occurred when the Von Mises stress was larger than the Orowan stress. The mobile dislocations density increases with γ plastic strain. The limiting mechanism for γ’ plastic strain is presumably the entry of dislocation within the γ’ rafts. Under this assumption we deduce the mechanisms of interactions between dislocations, vacancies, and pores within the material, and the mechanical behaviour of the γ’ rafts
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-01823534
Contributor : Abes Star :  Contact
Submitted on : Tuesday, June 26, 2018 - 10:29:25 AM
Last modification on : Monday, April 6, 2020 - 2:44:04 PM
Long-term archiving on: : Wednesday, September 26, 2018 - 8:39:05 PM

File

DDOC_T_2018_0055_TREHOREL.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01823534, version 1

Citation

Roxane Tréhorel. Comportement mécanique haute température du superalliage monocristallin AM1 : étude in situ par une nouvelle technique de diffraction en rayonnement synchrotron. Mécanique des matériaux [physics.class-ph]. Université de Lorraine, 2018. Français. ⟨NNT : 2018LORR0055⟩. ⟨tel-01823534⟩

Share

Metrics

Record views

144

Files downloads

346