Impact response of pre-strained pure vanadiumстатьяИсследовательская статья
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Дата последнего поиска статьи во внешних источниках: 16 июня 2022 г.
Аннотация:The effect of modest, 0.6% and 5.5%, pre-straining on the impact response of 2 mm thick samples of annealed polycrystalline vanadium of commercial purity was studied in a series of planar impact tests. The loading of the samples by 0.5mm thick copper impactors having velocities varying between 300 and 610 m/s was accompanied by continuous laser Doppler velocimetry of their rear surface. Based on the recorded velocity histories, the dynamic compressive σ_Y and tensile (spall) σsp strengths and the strength σ^sc_Y of vanadium in the shockcompressed state were determined. Adjacent to the impact surface part of the cross sections of the softly recovered samples, the number of twins Ntw per unit area was counted. It was found that the main parameter governing both the strength σ_Y of pristine (in the shock sense material and that in the shock-compressed state, σ^sc_Y , was the initial dislocation density η0. Moreover, the dislocation surplus caused by prestraining was responsible for complete suppressing of twinning in the 0.6% and 5.5% pre-strained samples. In undeformed vanadium, the twinning was partially suppressed by the presence of impurity atoms which, however, did not affect the twinning stress, which was equal to approximately 0.7 GPa.