Quenching and recovery investigations of vacancies in tungsten

Abstract

Abstract Resistivity and transmission-electron-microscopy investigations have been carried out on high-purity quenched tungsten. These have yielded values for the monovacancy formation and migration enthalpies of HIV F=3·67±0·2 eV and HIVM=1·78 ± 0.1 eV respectively, Direct observations of voids formed by vacancy precipitation during quenching and subsequent annealing have led to the conclusion that the equilibrium vacancy concentration at the melting point is Cv(Tm=3695 K) ≃ 1 × 10−4. Using this value, the vacancy resistivity and formation entropy, pIV=6·3 × 10−4 Ω cm and SIV F=2·3k respectively, were deduced. The results are discussed in relation to self-diffusion in tungsten and difficulties encountered in earlier work on quenched tungsten.