Plastic deformation and dislocation structure of molybdenum single crystals upon extending along 〈110〉 and 〈100〉 axes in the range from 77 to 573 °K

Abstract

An investigation is made of the dislocation structure forming upon straining high‐purity single crystals within the range from 77 to 573 °K. The single crystals were extended along the 〈100〉 and 〈110〉 axes. The dislocation structure observation was made in an electron microscope using thin foils cut from deformed specimens. It was established that screw dislocations uniformly distributed in size are predominant in the dislocation structure of deformed crystals at temperatures below room temperature irrespective of the axis orientation of extension. Increasing of the deformation temperature leads to the disappearance of the screw dislocations in the dislocation structure and to formation of a cellular structure. It is shown that at and below room temperature considerably higher growth rate of dislocation density with deformation is observed in crystals extended along the 〈100〉 axis. The dislocation density dependence on stress in crystals with 〈100〉‐orientation in the case of their extension at room temperature has been investigated also. The results obtained are well described by Takeuchi's theory of strain hardening.

Mechanical energy losses in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum at elevated temperatures

“…In addition, the dislocation density, determined by counting the dislocation lines, was larger in 〈110〉 than in 〈149〉 samples, in agreement with the multiple slip condition for 〈110〉 samples. Dislocations in samples with 〈110〉 orientation were shorter and present higher density of jogs than for the 〈149〉 orientation, which results in agreement with pervious reported works 23–27.…”

Interaction processes between vacancies and dislocations in molybdenum in the temperature range around 0.3 of the melting temperature

“…The dislocation structure of deformed molybdenum has been studied by (TEM) in the previous works [27][28][29][30][31]. Samples deformed at room temperature in the deformation range used in this work show screw dislocations with a high density of jogs but few edge dislocations.…”

Mechanical energy losses due to the movement of dislocations in molybdenum at high temperatures (0.3Tm)

“…The dislocation structure of deformed molybdenum has been studied by transmission electron microscopy (TEM) in other work [14][15][16][17][18]. Samples deformed at room temperature in the deformation range used in the present work show long screw dislocations with a high density of jogs but few edge dislocations.…”