|About this Abstract
||MS&T21: Materials Science & Technology
||Nucleation of Solid-State Phase Transformations
||Investigation of Nucleation Mechanisms Associated with the Formation of Coprecipitates in Ni-based Superalloys
||Hariharan Sriram, Semanti Mukhopadhyay, Michael Mills, Yunzhi Wang
|On-Site Speaker (Planned)
Experimental studies have shown a wide variety of γ'/γ” coprecipitates in IN718-based alloys. Although the coprecipitate's growth and coarsening mechanisms have been investigated, the heterogeneous nucleation mechanisms of γ” on existing γ' that lead to different types of coprecipitates are yet to be understood. We analyze the individual and combined effects of concentration field and coherency elastic stress field associated with existing γ' at different sizes on nucleation of γ", leading to different coprecipitate configurations. The chemical driving force for nucleation is calculated using the CALPHAD databases, while the contributions from elastic interaction and anisotropic interfacial energies between different interfaces are quantified by comparing results from phase-field simulation and experimental characterization. Subsequently, an explicit nucleation algorithm is used in phase-field simulations to study nucleation and early stage of growth. The study may shed light on how to achieve desired coprecipitate microstructures for increased thermal stability and enhanced mechanical properties.