In situ straining deformation of superalloys and intermetallics

In situ straining experiments provide the unique advantage of revealing the dynamic behaviour of crystalline defects under the combined effect of stre ss and temperature. These observations, in real time, allow the understandi ng and the quantitative analysis of deformation mechanisms. The examples of nickel base superalloys and lamellar TiAl alloys are developed. In these m ultiphase materials the stresses corresponding to the interface crossing ar e reached through the formation of pile ups of dislocations which produce a t their tip a stress approximately equal to the applied stress multiplied b y the number of dislocations involved, When comparing the yield stress of t he constituent single phase alloys and the two phase material important dif ferences exist which can be explained in terms of dislocation mobilities.