NONDESTRUCTIVE BULK DETECTION OF LOCALIZED STRAINING BY GAMMA-RAY DIFFRACTOMETRY - APPLICATION TO A SHEARED SINGLE-CRYSTAL OF CMSX3-2 SUPERALLOY

The gamma-ray diffraction technique is proposed as a means of detectin g and localizing strain in a bulk single grain material. In order to t est this non-destructive technique, a single grain nickel-base superal loy submitted to a pure shear creep test is studied. The study is base d on comparing a series of rocking curves recorded for the same parts of the sample before and after the shear test. The analysis of the roc king curves allows to detect relative rotations of different zones of the specimen, which results in the definition of a new geometry for th e sheared specimen. Moreover, the analysis of the diffraction peaks in relation to the sheared zone shows that gamma-ray diffraction is sens itive to straining; the position of the gamma-ray diffraction peak is modified and the diffraction peak collapses in the sheared zone. These results supplement the microscopic observations and confirm that the specific microstructure of the single crystal superalloy induces, afte r straining, a complex redistribution of the macroscopic deformation i n the material.