DEVELOPMENT OF SLIP LINES IN CONCENTRATED CU-BASED ALLOYS DURING WORK-HARDENING

The structure of slip lines evolving in alpha-phase Cu alloys with hig h solute concentration during the various deformation stages was exami ned systematically by light microscopy and electron microscopic replic as, similar as in the early work by Mader on pure Cu. Two types of cry stals oriented for single slip were investigated, i.e. Cu-8 at% Mn and Cu-10.7 at% Al, differing in stacking-fault energy, but both tending to short-range ordering. In stage I the alloys show similar patterns o f coarse slip (slip bands, slip band bundles. Luders bands) but differ distinctly in their fine structure of slip. The difference increases with deformation (stage II), in Cu-Al the slip pattern varies strongly along the crystal indicating heavy fluctuations of internal stresses, contrary to Cu-Mn where slip evolution closely resembles that in pure Cu. In stage III both alloys show fragmentation of the slip bands as known from pure Cu. The microscopic reasons for these results are disc ussed in terms of the interplay between solid solution hardening, shor t-range ordering and stacking-fault energy.