Modelling of deformation plasticity and texture evolution in NiAl polycrystals

Abstract

We present experimental results for texture evolution in NiAl polycrystals under compression at elevated temperatures of initially extruded samples. Based on these experimental observations and on existing experimental results, we discuss the operating slip systems in NiAl and address the lack of five independent slip systems in this ordered intermetallic material. We also propose the use of crystal plasticity modelling to simulate texture evolution in NiAl. We use the projection model of Parks and Ahzi which accounts explicitly for the missing degrees of kinematic freedom due to the activation of only three independent slip systems in NiAl crystals. Different sets of slip systems were used in this model and in the Taylor model to simulate texture evolution under uniaxial tension of initially isotropic NiAl polycrystals, and uniaxial compression of initially textured polycrystals. The contribution of each set of slip systems to texturing is discussed. Predicted results are compared with experimental observations. We conclude that the use of the projection model with the three independent slip systems, experimentally observed to operate at elevated temperatures, leads to texture predictions in good agreement with experiments.