Abstract
Variation of flow stress of tin single crystal is examined by applying to it successive impacts by means of two similar pendulums weighing 180g each, -one with the specimen fixed at its end which is hit by the swinging weight of the other-instead of applying a single strong impact as is usually practised. Results of observation are as follows.
Behavior of impure tin crystals grown from melt of 99% tin was found strongly dependent on impact velocity. At 28cm/sec velocity, general yielding occurred, while at 24 cm/sec, discontinuous slips were seen. At smaller velocities of 20, 16, 12 and 9cm/sec, there were almost elastic collisions, but when the velocity was further reduced to 6cm/sec, a small amount of slip in discontinuous steps was noticed. At large velocities, rapid age-hardening was observed but not at 6cm/sec. In as-grown specimens, the discontinuous slips were indistinct and general yielding occurred more readily than in annealed specimens. In purer specimens grown from melt of 99.99% tin, the slip proceeded smoothly irrespective of impact velocity.
The above results seem to be explainable by a mechanism similar to that of Liiders band observed on mild steel.
