ON THE RELATION BETWEEN DISLOCATION-STRUCTURE AND INTERNAL-STRESS MEASURED IN PURE METALS AND SINGLE-PHASE ALLOYS IN HIGH-TEMPERATURE CREEP

A survey of experimental studies of a relation between dislocation structure and internal stress sigma-i measured by means of the strain transient dip test technique in high temperature (mostly steady-state) creep of various metals and single phase alloys is given. Application of various approaches, i.e. direct evaluation of sigma-i from quantitative structure data. correlation of sigma-i and parameter of dislocation strengthening Gb square-root-rho (G is the shear modulus, b Burgers vector length and rho dislocation density), stochastic model of sigma-i in a three-dimensional dislocation network, reveals the problem of strengthening by a homogeneously distributed dislocation density from several points of view. Attention is paid to the strengthening effect of polygonized substructure. Discussion of the presented results leads to conclusions about various sources of internal stress in the dislocation structure and substructure formed in creep and about the influence of temperature on dislocation structure in relation to the temperature dependent measured internal stress.