Studies of point defects by positrons and positive muons

Positron annihilation and positive muon spin relaxation techniques can be applied to the study of point defects. By positron annihilation the formation energies of a vacancy have been measured in many pure metals and alloys. Positron annihilation is quite sensitive to small vacancy clusters which cannot be observed by electron microscopy. Positive muons can be also used to study vacancy type defects. Quenched-in vacancies in pure aluminum and aluminum dilute alloys have been quantitatively studied. These techniques can be used as one of the non-destructive testing techniques. (author)