Predicting interface behavior and final geometry in multi-material spark plasma sintering: design insights from validated multiphysics process modeling

Multi-material spark plasma sintering (SPS) enables architected components with tailored properties, but it also poses challenges in controlling differential densification, geometric precision, and interface alignment under complex electro-thermo-mechanical conditions. Because experimental trial-and-error provides only limited insight into these coupled mechanisms, predictive process modeling is needed. Here, we develop and experimentally validate a fully coupled electro–thermo–mechanical finite element model for multi-material SPS of copper-nickel systems. A central contribution is the direct transfer of porosity-dependent constitutive parameters, independently calibrated from single-material SPS experiments, to multi-material configurations, without any additional fitting. The model accurately captures the temperature and densification evolution across three representative interface orientations (horizontal, inclined, and vertical), with deviations below 1 %, providing a quantitative validation of parameter transferability. From an engineering perspective, the framework predicts final geometries and interface displacements with dimensional errors below 7 %, enabling predictive design of powder deposition and interface placement. The simulations further show that interface orientation controls current-path distortion and localized Joule heating in highly conductive materials, whereas differences in porosity are the dominant driver of interface displacement. Beyond the Cu–Ni system studied here, the proposed multiphysics framework provides a transferable modeling strategy to support geometry control and interface design in thermomechanically similar multi-material SPS components. • Final geometries and interface displacements predicted with 93 % accuracy. • Interface orientation affects temperature and densification. • Initial porosity imbalance and interface position influence interface alignment.