Composition dependence of surface and bulk defects generated in Cu-Zn-Al single crystals after pseudoelastic cycling

The effect of composition on the microstructural evolution after fatigue is presented for Cu-Zn-Al single crystals. Fatigue associated to stress-induced martensitic transformations has been shows to induce several types of defects in poly and single crystals of Cu-Zn-Al alloys, the grain boundaries playing the main role in the polycrystals. In this work attention is paid to the formation of defects on the surface and in the bulk for single crystals of different compositions, and similar defects to those found for transformation temperatures M(s), around room temperature and e/a = 1.48 are seen for e/a = 1.43 but after a much smaller number of cycles. However, changes in the mechanical behavior are not observed at least up to 1000 cycles, even though the changes on the surface and in the bulk for the latter composition are striking. (C) 1999 Elsevier Science S.A. All rights reserved.