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

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 τ^I acting at the primary glide systems of KBr, of the transformation pressure p_tr, and of the characteristic transformation time t_tr were determined.