Nanoindentation size effects of mechanical and creep performance in Ni-based superalloy

Nanoindentation technique was adopted to study indentation size effects of physical-mechanical and creep performance with various depths (200-2000 nm) in GH901 utilising sharp and spherical tip. Residual impressions of both indenters with pile-up patterns are discussed. Nanohardness, reduced modulus and elastic recovery rates curves versus maximum displacement of two tips are obtained and nanohardness size effects are discussed with different models for Berkovich tip. The data obtained with spherical indentation are analysed separately by establishing stress-strain diagram. The creep results using Berkovich tip indicate that creep strain rate declines while creep stress exponent first decreases and then increases with the increasing depth; the creep stress exponent (n) values, 2.39-7.35, imply the dominant creep deformation mechanism is dislocation control.