A quantitative study of vacancy defects in quenched tungsten by combined field-ion microscopy and electrical resistometry

A study of quenched, high-purity tungsten has been carried out with a combination of field-ion microscopy (FIM) and electrical resistivity measurements. It is concluded that the quenched-in vacancy defects observed by FIM are monovacan-cies and nearest-neighbour divacancies. From the partitioning during quenching between these two species, a divacancy binding enthalpy H2V b≃0·7eV is deduced. A monovacancy resistivity of 7 × 10−4 Ω cm is obtained from the combined measurements. The quenched-in vacancy concentrations measured directly by FIM are consistent with previous results, if the total vacancy concentration at the melting temperature of tungsten (3695 K) is about 3 × 10−4 and the monovacancy formation enthalpy and entropy are 3·6 eV and 3·2k, respectively. The results are discussed in terms of the atomic-defect mechanisms for self-diffusion in tungsten.