Local Strain Accommodation in Polycrystalline Ni-Base Superalloys [chapter]

Jennifer Walley, Robert Wheeler, Michael D. Uchic, Michael J. Mills
2011 Time Dependent Constitutive Behavior and Fracture/Failure Processes, Volume 3  
To exploit new hybrid nickel-based superalloys, physics-based computational models are needed to predict material properties and describe material behavior during exposure to complex life cycles. Such models will allow an iterative assessment of microstructural morphology as related to mechanical properties prior to production of large-scale test specimens or components, thereby reducing development time and cost. Development of these models is currently hindered by a gap in the understanding
more » ... local deformation behavior at the intra-and intergranular level. A new in-situ experimental methodology is being developed to characterize local strain heterogeneities in nickel-based superalloys that have a relatively fine grain size (d ave <50μm). Initial work has been performed on Rene 104 that was heat treated to produce two sets of samples with a similar grain size but different γ' distributions and grain boundary morphologies. One sample set had planar boundaries and a bimodal γ' distribution, the other set had serrated boundaries and a trimodal γ' distribution. Progress has been made towards implementation of a suitable speckle pattern for digital image correlation (DIC). Quasi-isostatic room temperature tensile tests were performed in a scanning electron microscope, with images acquired at regular strain intervals. This preliminary data was qualitatively analyzed using Correlated Solutions VIC-2D software. The data for the serrated boundaries indicates that there are indeed interesting strain heterogeneities being developed that are related to grain orientations, boundary relationships to the tensile axis and other boundaries.
doi:10.1007/978-1-4419-9794-4_7 fatcat:krngszjhrjcv5ohuyncgfbwu6i