Dynamic Hardness Evolution in Metals from Impact Induced Gradient Dislocation Density

Investigation on Shock Metamorphism of Anatase by Supersonic Microprojectile Impact

“…The projectile’s launching velocity is dependent on the characteristics of the projectile, ablation laser energy, and the launch pad structure. Recent studies using the same LIPIT technique offer detailed descriptions of the technique. − The laser energy was tuned for the launch pad we used to be about 0.56 mJ/pulse by utilizing an attenuator to launch the 9 μm silica sphere at 450 m/s. A high-resolution microscope camera (Allied Vision Mako G-234B with OPTEM FUSION 12.5:1 lens) was used to capture images of the projectile in flight at 103 ns intervals by picosecond laser pulses from a supercontinuum white laser (NKT photonics EXR-20) externally shuttered by an acousto-optic modulator.…”

“…With the discovery of naturally occurring shock-induced TiO 2 polymorphs such as srilankite and riesite, a deep understanding of the TiO 2 phase relations is required to constrain the shocked metamorphic conditions in earth and planetary systems. ,, In this study, we investigate the shock metamorphism of anatase induced by supersonic microprojectile impacts using a laser-induced projectile impact testing (LIPIT) technique. The LIPIT methodology is a novel approach for testing shock metamorphism on a mineral surface. − The phase transformation behavior of shocked phases was studied using a 3D digital microscope, synchrotron X-ray diffraction (XRD), focused ion beam/scanning electron microscopy (FIB/SEM), transmission electron microscope (TEM), and density functional theory (DFT) calculations. The structures of the obtained TiO 2 polymorphs are characterized by Rietveld refinement, selected area diffraction patterns (SAED), and high-resolution TEM (HRTEM) with fast Fourier transform (FFT) patterns.…”