The spall strength and Hugoniot elastic limit of mono-crystalline and polycrystalline copper near melting temperature Academic Article uri icon

abstract

  • In present work, the Hugoniot elastic limit (HEL) and spall strength of polycrystalline commercial grade copper and single crystal copper of <100> and <111> orientations were determined for sample temperatures varying from 20 to 1081°C. The differently preheated samples whose thickness varied between 0.5 and 2 mm were shock-loaded by copper plates of 1-mm thickness accelerated up to 300-400 m/s velocity in the 58mm smooth bore gas gun, or by aluminium plates of 0.4 mm in thickness (~660 m/s), accelerated with explosive facilities. The velocity histories of the free rear surface of the loaded samples were recorded with VISAR laser velocimeter. The velocity histories of the samples of polycrystalline copper demonstrate 9-fold growth of the stress at HEL between room and melting temperatures. Unlike other metals commercial grade copper maintains very high spall strength near the melting point Tm; it is only twice as low as that of the copper at 0.85 Tm. The copper single crystals of both orientations also demonstrate substantial spall strength at 0.94 Tm (1000°C). At the same time, the increase of the stress at HEL with temperature in these samples is much weaker than that found for polycrystalline samples of copper.

publication date

  • January 1, 2014