Solid-state bonding can form when metallic microparticles impact metallic substrates at supersonic velocities. Such impacts induce extreme deformation and pressure, fracturing the native oxide layer and bringing metallic surfaces into close proximity to form metallic bonds. While conditions for impact-induced bonding are relatively well understood, the bonding mechanisms and the resulting interfacial properties remain elusive. Addressing these open questions is the focus of this dissertation.First, fracture modalities of metallic particle surface oxide layer under compressive loading were resolved. Three distinct modalities, meridian, radial, and circumferential cracks, activate sequentially with increasing particle flattening, along with strengthening effects from both the composite strengthening of the oxide layer and strain-gradient strengthening within the metallic particle. Supersonic impact induces ultra-high-strain-rate deformation in metals, which is governed by dislocation-phonon interaction. An impression-based scheme combining laser-induced microprojectile impact test (LIPIT) and spherical nanoindentation was developed to quantify the phonon-drag regime and to calibrate a physically-based constitutive model for particle impact predictions. Well-controlled, isolated bonded particles were produced using LIPIT, followed by micromechanical tests to measure the interfacial properties. A gradient of bond strength along the interface was both measured and theoretically predicted, starting with weak bonding near the impact center, followed by a rapid twofold rise to a peak strength, which continues as a high-strength plateau towards the periphery. The morphology of the native oxide at the interface was found to dictate the bond strength. In addition, the effect of impact velocity and particle size on interfacial strength were studied. A peak-strength velocity was identified followed by decreasing strength at higher velocities due to adiabatic-softening-induced intensified elastic recovery damage. Increasing particle size facilitates stronger bonding through reduced deformation strain rate, which results in prolonged and stronger bonding and more distributed plastic deformation reducing elastic recovery damage. In summary, these studies establish fundamental understanding of impact-induced bonding, spanning high-strain-rate deformation mechanisms, bonding mechanisms, and the resulting interfacial properties. The scientific insights, along with the developed experimental and numerical frameworks, will help in optimizing impact-based solid-state additive manufacturing with tailored interfacial strength and reliability.