LARGE-STRAIN DEFORMATION OF NI3AL+B .1. MICROSTRUCTURE AND TEXTURE EVOLUTION DURING ROLLING

The microstructure evolution and texture development of the intermetallic compound Ni76Al24, doped with minor additions of boron was investigated in great detail as a function of rolling reduction at ambient temperature. The microstructure was found to become extremely inhomogeneous by formation of microbands (MB) and shear bands (SB). Dislocation cell formation was not observed. The microstructure development is interpreted in terms of forced planar slip in the Ll2 crystal structure. This causes strong work hardening and destabilizes deformation by slip while shear-band formation is promoted. The rolling texture is very weak and resembles a weak copper-type texture up to high degrees of rolling. The strongest component is the brass orientation ({110}[112]) after large rolling reductions; it is attributed to orientations inside shear bands. No deformation twinning was observed, even for deformation at liquid nitrogen temperature.