Temperature dependence of dislocation mobility in molybdenum monocrystals

In molybdenum monocrystals of two impurity compositions (the ratio of specific electric resistances rhosub(300 deg K)/rhosub(4.2 deg K) approximately = 3x104 and approximately 2x103 with orientations of loading axe <11 anti 0> and <010> the method of selective etching and pulse loading is applied to study the mobility of newly introduced (close to screw) dislocations in rose rays (glide systems [112] <11 anti 1 >) at T=300, 77 and 4.2 deg K. In the above temperature range the motion of dislocations occurs in the velocity interval v=10-1 - 10-6 cm/sec at stress values that are considerably smaller than the yield limit of such crystals. The mobility of dislocations turns out to be different for Mo of different compositions, and the decrease of T is accompanied by the increase of the difference in the dislocation mobility. It is shown that the dislocation motion is governed by Schmidt law while the asymmetry of dislocation glide during stretching and compression is absent. The dependences v(T) obtained have been used to estimate the values of activation parameters for the motion of dislocations