A Cu:Hf sample with 1wt%Hf as prepared by arc melting was characterized by transmission electron microscopic and microdiffraction analysis to contain HfC precipitates. HfC precipitates in a Cu matrix bind vacancies and divacancies strongly in the quenched Cu:Hf sample as deduced by time differential perturbed angular correlation (TDPAC) studies. Isochronal annealing studies using TDPAC and positron lifetime measurements indicated the stability of these vacancy complexes in the quenched sample for annealing treatments up to 1200K, beyond which the de-trapping of the vacancies from HfC precipitates was observed to occur. This showed that HfC precipitates present in Cu inhibit the formation of voids by strongly binding quenched vacancies.

Interaction between HfC Precipitates and Vacancies in Quenched Cu:Hf as Studied by TDPAC and Positron Lifetime Measurements. R.Govindaraj, R.Rajaraman: Journal of Physics - Condensed Matter, 2004, 16[34], 6579-6588