High temperature creep of molybdenum and tungsten single crystals substructure strengthened

摘要

The creep rate #epsilon#~centre dot (at 0.57 - 0.61 T_m and 5centre dot10~(-5)-3centre dot10~(-4) G(T), where T_m is melting point, G(T) is sheer modulus) of Mo and W single crystals subjected to different treatments is determined by integral substructure parameter & (integral substructure misorientation angle) #epsilon#~centre dot approx &~(-2) and does not depend on preliminary treatment kind in explicit form. & is found by X-ray method on azimuthal reflex widening. & approx triangle opennD_f where triangle openn is one sign excess dislocation density, D_f is the correlation area size of one sign dislocations. The creep mechanisms of single-crystalline Mo and W in initial and strengthened states were found. It was revealed by electron microscopy that strengthening magnitude depends mainly on long range stress fields level from small angle subboundaries. These fields depend immediately on dislocation structure of such subboundaries.