Deformation Mechanisms in Nanoscale Heterostructured Binary and Multicomponent Metallic Eutectics

Rapid solidification in the melt pool during laser additive manufacturing can lead to far-from equilibrium microstructures in metallic alloys. This presentation will highlight the use of laser rapid solidification in nanoscale refinement of eutectic microstructure in light-weight Aluminum based alloys such as Al-Al2Cu, Al-Si and Al-Si(Sr). These alloys display unusual mechanical behavior where both strength and ductility increase with multi-phase refinement and plastic flow becomes more homogeneously distributed with increasing microstructural heterogeneity.

In situ tensile testing in scanning electron microscope (SEM), and high-resolution scanning transmission electron microscopy (HR-STEM) characterization reveal new dislocation mechanisms in laser-refined nanoscale eutectics that are not observed in the bulk micro-structured as-cast alloys. Molecular dynamics simulations are used to discern the critical dislocation mechanisms of slip transmission and strain hardening. The deformation mechanisms in nanoscale binary eutectics can also explain the improved mechanical properties reported in the so called “high entropy” eutectics.