Fig. 4: Deformation mechanism in laser powder-bed-fusion copper nanocomposites.

a Strain mapping analysis of grains in Cu-12%-ANP and Cu-12%-CNP nanocomposites after tensile strain of 3%, as obtained from high-resolution EBSD (HR-EBSD) images. CNP refers to a crystallized nanoparticle. The zero-stress reference point is chosen as the position with the lowest kernel average misorientation (KAM). b Representative two-beam bright-field TEM image of the deformed Cu-12%-ANP nanocomposites (3% strain). The right column shows the inverse pole figure (IPF; top panel) map of the selected region, with the associated image quality map superimposed. The data are acquired using precession electron diffraction (PED)-based automated crystal orientation mapping (ACOM) in a TEM with a step size of 1 nm. Three experiments were repeated independently and get the similar results. Plots of the variation in the misorientation angle, measured with respect to the origin and from point to point, across the representative ANP after deformation, indicated by the solid black line in the IPF map. c Changes in the lattice strains in Cu-8%-ANP and Cu-8%-CNP nanocomposites against macroscopic true stress for representative FCC (including {111}, {200}, {220}, {311} and {222}) crystallographic plane families along the loading direction. The experimental and crystal plasticity finite element (CPFE) modelling results are represented by symbols and solid lines, respectively. The macroscopic yield strengths of the different samples are marked with dashed lines. d CPFE simulation results of the macroscopic stress–strain responses with the corresponding stress partitioning in the copper matrix and nanoparticles. e Snapshots of the forward-moving dislocation interacting with the primary ANP, as observed in molecular dynamics (MD) simulations. The corresponding maps showing the atomic von Mises strain in copper are displayed in the right panels. f Corresponding von Mises shear strain maps in the ANP and CNP after dislocation bypassing. The whole deformation process of nanoparticles in different samples can be seen in Supplementary Movies S2 (for ANP) and S3 (for CNP). g Changes in the relative potential energies of atoms in the ANP (energy change relative to its original state) as functions of applied shear strain.