Work hardening of fine grained materials

The temperature dependent work hardening behaviour of aluminum alloy AA5754 and 99.99% copper with grain sizes in the range of 1 - 15 mum is examined in this work. In the case of the aluminum alloy, it is observed that Ludering develops both at room temperature and at 77 K but only for samples with a grain size < 10 mum. On the other hand for copper, no Ludering is observed but a regime of low work hardening rate follows yielding. The results of these experiments are compared and contrasted to the 'classical' description of the effect of grain size on work hardening rate in the Kocks-Mecking frame work.