NaCl crystals were subjected to low velocity impacts provided by a drop weight impact machine. The shear bands were imaged with the use of arrays of fast responding infrared detectors. The detectors monitored the amount of energy given off as infrared photons by the impacted crystalline solid. The main emphasis of this study was the real time observance of the shear band formation during the impact. The signal was recorded over the duration of the impact, heating I of the solid during its crushing, and the relaxation of the crystal. These crushing processes occurred over a 40-100 ,us timescale. Rapid infrared photons corresponding to shear banding were recorded on a 30-90 ns timescale.

This paper describes in detail the experimental procedures and apparatus involved in experiments that observe the real-time formation of shear bands in NaCl crystals during deformation due to impact. The crystals, impacted at low velocities of 5–20 m/s, emit rapid (30 ns) infrared emissions. An array of fast responding infrared detectors formed images which indicated that the shear bands form within a few tens of nanoseconds.

This paper discusses experimental results from an effort conducted to discern the basic mechanism of reactions in porous metal/metal compositions under rapid plastic flow conditions. Small-scale impact tests were performed on various intermetallic mixtures: 3CuO + 2AI, Fe2O3 + 2AI, Ni + Al, and 5Ti + 3Si. The addition of polytetrafluoroethylene (Teflon) to the metal/metal mixtures has been demonstrated to affect the extent of the reactions. Real-time emissivity and species evolution measurements of the reacting materials were used to discern the chemical reactions occurring under rapid plastic flow conditions.

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