Quenching and recovery investigations of vacancies in tungsten

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 ofHsub(IV)sup(F) = 3.67+- 0.2 eV and Hsub(IV)sup(M) = 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 Csub(v)(Tsub(m) = 3695 K) approximately equal to 1 x 10-4. Using this value, the vacancy resistivity and formation entropy, sub(rhoIV) = 6.3 x 10-4 Ω cm and Ssub(IV)sup(F) = 2.3k respectively, were deduced. The results are discussed in relation to self-diffusion in tungsten and difficulties enountered in earlier work on quenched tungsten. (author)