Low-temperature anomalies of mechanical properties in Zn-Cu-Ti single crystals

The paper presents the results of tests carried out on single crystals of Zn-Cu-Ti. Through proper choice of the crystal growth rate, three types of structure were obtained which, besides differences in the shape and distribution of the Zn16Ti phase precipitates, also differed in the microsegregation of elements (Cu, Ti) in the matrix. The study showed the occurrence of anomalies in the strain hardening exponent at about 240K. The intensity of those anomalies was strongly dependent on the type of the structure examined. Moreover, it has been found that under the applied conditions of deformation (compression test, strain rate), a periodical activation of the jerky flow effect takes place. The range of conditions favourable for the jerky flow activation in a temperature-stress system is confined by a parabola. Its minimum is convergent with the temperature at which the strain hardening exponent shows the presence of the anomaly. This proves the same origin of both phenomena.