Mechanical behavior of polycrystalline tungsten at elevated temperature

摘要: Abstract The influence of stress, temperature, grain size and subgrain on the steady state creep rate polycrystalline unalloyed tungsten has been examined based extensive published data available. It was shown that tungsten, other metals, is given by ϵ = Sλ 2 Deff ( σ E ) 7 where λ size, average unrelaxed elastic modulus, S a universal constant equal to about 3 × 1040 cm−4. effective diffusion coefficient, Deff, equals D L ƒ + DL lattice DD dislocation are fraction atoms participating in respectively. When subgrains form during creep, as normal behaving materials, kσ−1 (k material constant) above equation yields generally observed five power stress law for creep. do not (as many refractory metals produced powder metallurgy techniques), replaced size. In this case αL ;αL , predictions agreement with experimental evidence. breakdown at high stresses can be explained one two possibilities 1. (i) creation excess vacancies plastic deformation which increases term 2. (ii) increase density increasing influences term, Deff.