(Pierre BASTIE., in coll. with Institut Jean Lamour (Nancy), LGGE (Grenoble), IRAP (Toulouse) and SSL (Berkeley))
Nickel based superalloys
The correlation between microstructure and mechanical properties was analysed “in situ” by high energy synchrotron X ray diffraction. In particular, tests under variable stress allows us to determine the behaviour of each phase during deformation at high temperature and to follow the evolution of the density of mobile dislocations.
The dislocation distribution was analysed on single crystal samples deformed by torsion. Long range spatial correlation controls the distribution at low strain level while short range correlation prevails with increasing strain.
Studies to find the most efficient
crystals for building a Laue lens for gamma telescope were pursued. The interest to use curved crystals was demonstrated and methods to obtain, in a reproducible way, well controlled curved crystals were tested. At last, experience analysis are in progress on phase coexistence at the a – b quartz transition and on plasticity of solid helium.