Recovery features in rolled tungsten single crystals of various purity

The deformation behavior of tungsten single crystals with various purity was studied. Single crystal sheets were prepared The sheers retain the as-grown orientation at all stages of rolling deformation and only polygonization, which preserves the single cn stal structure, takes place in samples heated to the temperature close to the melting point. The subboundaries formation proceeds in two stages with subsequent transformation of the unstable structure into a configuration having all energy minimum. The decisive factor affecting the polygonization rate is the stacking fault energy. The presence of impurities has also a significant influence. Some common? structural features for molybdenum, tungsten and niobium single crystal during deformation and subsequent annealings were discussed.