HYDROGEN INFLUENCE ON MARTENSITIC-TRANSFORMATION AND SHAPE-MEMORY EFFECT IN TITANIUM-ALLOYS

The influence of hydrogen alloying on the habitudes of martensitic tra nsformation (MT) in (alpha+beta)-titanium alloys was investigated. It was shown, that increased hydrogen content in titanium alloys lowered the temperature and widened the range of direct and reverse MT, it als o lowers the critical cooling rate over which the MT occurred. Thus, h ydrogen in the process of cooling facilitates the (beta double right a rrow alpha'')-transformation, and it can be realized even in alloys, i n which without hydrogen the (beta double right arrow alpha')-martensi tic transformation takes place. The dislocation mechanism of deformati on with invariant lattice during MT mostly changes to the twinning. Th e increased hydrogen content lowers the absolute value of the main def ormations of (beta double right arrow alpha'') MT and one of them tend s to zero, the habit of a crystal has more perfect structure and highe r mobility. Hydrogen enriched alloys have necessary conditions for con servation of coherence on interface boundaries in the range of (beta d ouble right arrow alpha'') MT In its term, it causes near complete sha pe memory effect realization. So, the hydrogen increased titanium allo ys of martensit class have recovering deformation effect in 1.5 times higher than alloys with ordinary hydrogen content.