Crystallographic orientation influence on slip system activation and deformation mechanisms in Waspaloy during in-situ mechanical loading

Abstract

The deformation mechanism correlations with individual grain orientation, overall texture, grain boundary characteristics, dislocation accumulation and evolutions were investigated during in-situ room temperature tensile testing of a nickel-based superalloy, Waspaloy. During tensile testing, electron backscatter diffraction (EBSD) mappings, as well as electron microscopy images were acquired at increments of displacement to observe the exact deformation mechanics in different orientated grains during plastic deformation. Here, it is demonstrated that Cube (001)<100> orientated grains were readily rotated and Copper (112)<111> texture component area fraction increased during loading. It was also shown that Cube orientated grains behaved as “soft” grains and easily activated an available octahedral (111)<1–10> slip system through simple shear mechanisms, allowing for easy dislocation movement and accumulation within the grain. On the contrary, Brass (011)<211> grains acted as “hard” and most stable orientation as they were not favourably orientated for octahedral (111)<1–10> slip system activation. The response variations to external loading from different orientated grains created a high strain incompatibility between neighbouring grains causing high GND density within the grains and along grain boundaries depending on the grain’s orientation.