The annealing of deformed potassium

Measurements of length-change have been used to study the recovery of high-purity potassium deformed by compression at 1·2 K. There is a large annealing band between 1·2 and about 20 K, the relative length-recovery rate being roughly constant at about 2 × 10−5 K−1, the total length-increase being about 1% of the original plastic compression. The recovery spectrum is quite different from the 15 K point-defect stage observed in resistivity studies on cold-worked potassium. It is shown that the point-defect recovery stage is not affected by dislocation movement involved in the length recovery, which itself reflects a strong temperature dependence of internal stress due to thermal activation over some obstacle to dislocation motion, perhaps the Peierls-Nabarro stress.