Bulk Defects in Pseudoelastically Cycled Cu-Zn-Al Single-Crystals

The pseudoelastic behavior, in Cu-Zn-Al alloys cycled between the bcc phase (β) and the 18R martensite structure was analyzed for tests performed within the range [-196 °C - 50 °C]. The role of the temperature, in these fatigue experiments, is pointed out by a different evolution of the σ-ε curves with cycling, which are related with changes in the nature and density of the defects formed in the bulk

Recoverable Effects Related to Pseudoelastic Cycling in Cu-Zn-Al Single Crystals

Pseudoelastic cycling of Cu-Zn-Al single crystals has been shown to induce microstructural changes in the material. The mechanical response is also altered. However, some of the observed changes in the mechanical behavior are at least partially recovered at temperatures at which point defects are mobile. In this work results are presented in order to analyze the different contributions associated to the changes of the mechanical behavior during pseudoelastic cycling and in a subsequent ageing stage in the β-phase condition for Cu-Zn-Al single crystals. The magnitudes and kinetics of the recoverable changes are analyzed and compared with the other known phenomena that take place at these temperatures, i.e. the martensite stabilization and the beta phase recovery. Results show that the evolution is not simply related to these phenomena. Additional contributions, like point defects generation during cycling and the effect of dislocation array on the beta phase recovery, need to be considered