Impact response of potassium bromide in 166–880 K temperature range

Abstract

The impact response of potassium bromide single crystals with ⟨100⟩ and ⟨110⟩ orientation was studied in a series of planar impact experiments under continuous monitoring of the sample rear surface velocity. The samples whose initial temperature varied between 166 and 880 K were loaded with aluminum, copper or tungsten impactors having velocities ranging from 140 to 690 m/s. The velocity histories recorded in the experiments with maximum compressive stress, lower than about 2 GPa, include the elastic precursor wave followed by the plastic wave, while the waveforms, recorded in the experiments with stronger loading, are characterized by a three-wave structure caused by the shock-induced B1→B2 phase transformation in KBr. On the basis of the recorded velocity histories, the temperature dependences of the shear stress τI acting at the primary glide systems of KBr, of the transformation pressure ptr, and of the characteristic transformation time ttr were determined.