Positron annihilation in Co alloys containing FCC and HCP phases

Positron annihilation is studied in CoCu and CoMn alloys subjected to the heat treatments which result in the structural states with various lattices, phase contents and defects concentrations. The positrons are shown to be insensitive to the hcp layers in fcc lattice which form the stacking faults. Multiple transitions through the interval of martensitic transformation initiate the formation of defects of the higher concentration the larger of the volume effect of transformation.