Fig. 1: In situ single particle impact test and site-specific measurements of bond strength.

a Schematic of the laser-induced microprojectile impact testing (LIPIT) setup. Multi-exposure images showing b a 22-µm Al microparticle impacting and an Al substrate at 752 m/s and rebounding and c a 22-µm Al microparticle impacting an Al substrate at 1066 m/s and bonding to it. d Top view of an Al particle bonded onto an Al substrate at 1100 m/s. e Cross-sectional view of the Al particle shown in (d) showing the bonded interface and locations of microtensile specimens on the interface. f A microtensile specimen micromachined from bonded particles, and then fractured at the interface during microtensile testing. g Experimental measurements of bond strength at the micron scale reveal a gradient of bond strength across impact-induced bonded interfaces for 23 ± 2 μm Al particles impacting and bonding onto an Al substrate at 1100 ± 41 m/s. The error bars in x coordinate on the experimental data points are the width of the microtensile specimens at the gauge section. The error bars in y coordinate on the experimental data points are calculated from the resolutions of microtensile load recording and SEM characterization of specimen geometry. The geometry of the deformed particle and substrate was superimposed on the plot as colored regions to enhance clarity. Source data are provided as a Source Data file.