To understand in more detail the behaviour of deformed metallic materials, the knowledge of defects and defect distributions at an atomistic level is important. To investigate the plastic zone in front of a crack tip, the positron annihilation lifetime spectroscopy with a pulsed monoenergetic positron beam of variable energy allows the detection of vacancies, dislocations, vacancy clusters and micro voids in the crack surface near region. Moreover, for a given defect type it is possible to determine its concentration. The positron lifetime measurements in samples of different materials (aluminium, copper) showed different defect profiles for crack surfaces produced by monotonic and cyclic deformation. In addition, this technique was able to characterize the kind of damage (monotonic or cyclic) by analysing the different positron lifetimes. © 2010 IOP Publishing Ltd.    «

To understand in more detail the behaviour of deformed metallic materials, the knowledge of defects and defect distributions at an atomistic level is important. To investigate the plastic zone in front of a crack tip, the positron annihilation lifetime spectroscopy with a pulsed monoenergetic positron beam of variable energy allows the detection of vacancies, dislocations, vacancy clusters and micro voids in the crack surface near region. Moreover, for a given defect type it is possible to deter...    »