Experimental Data Evolution of Structural Parameters

A theory of strength of metals at high temperatures has to be based on experimental data. An experimental technique was developed for in situ X-ray investigations of metals and alloys directly during creep process [79]. The structural peculiarities of the high-temperature strained metals were also studied by transmission electron microscopy (TEM). Our goal was to obtain data that enable us to observe the events on atomic and microscopic levels. 

Some regularities are revealed as the result of systematic examinations of the bright- and dark-field image pictures and diffraction patterns of a large number of specimens. 

Most of the dislocations in specimen after high-temperature tests are associated in sub-boundaries. The parallel sub-boundary dislocations are situated at equal distance from each other. It follows from results of the Burgers vector determinations 

The first dislocation system is directed along [110] with the Burgers vector fei = a/2[111], the second along with 2 = /2[li 1]. The plane of the foil is (210). 84000 x. 

The regular dislocation networks as low-angle sub-boundaries are found to be typical for the high-temperature tested metals. 

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