The yield point of GaAs:Zn pre-deformed in the Peierls regime

In previous work by the present authors, the influence of pre-deformation at 600°C on the strain-rate and temperature dependence of the yield point of GaAs:Zn was investigated. Marked deviations in comparison with the behaviour of as-grown material were found in subsequent deformation at lower temperatures. In the present study the specimens were pre-deformed at 420°C, and the second tests were performed at temperatures between 270 and 390°C. This is the range in which the dislocation motion governing plasticity is dominated by a Peierls mechanism. Again, marked deviations from the properties of as-grown material were observed. They are mainly characterized by a distinctly smaller strain-rate dependence of the yield stress. Only close to the ductile-brittle transition in a rather limited temperature and strain-rate range does the behaviour of pre-deformed crystals approximate that of as-grown material.