Evaluation of the stress-strain relationship of constituent phases in AlSi10Mg alloy produced by selective laser melting using crystal plasticity FEM

Abstract

The present study was an evaluation of the stress-strain relationship between Al and Si constituents in AlSi10Mg alloy produced by selective laser melting (SLM) under uniaxial tension at room temperature. In-situ neutron diffraction was used to separately measure the (311) lattice strains of Al and Si phases as a function of macroscopic stress. The crystal plasticity finite element method (CPFEM) was utilized to determine the microscopic hardening parameters for constituent phases by fitting the macroscopic stress response and lattice strain measured by in-situ neutron diffraction. Digital image correlation (DIC) revealed that deformation heterogeneity yields diffuse necking followed by fracture that can be caused by only a small amount of plastic deformation. High-resolution TEM analysis provided evidence of plastic deformation by the formation of stacking faults and mechanical twins in hard Si nano particles in the Al matrix. This elucidates the highly nonlinear elastic-plastic stress-strain relationship of the Si phase, as measured by in-situ neutron diffraction.