Effect of one variant of Ti3Ni4 particles on stress-induced martensitic transformations in <111>-oriented Ti49.2Ni50.8 single crystals

Abstract

In the present study the effects of stress-assisted aging of the Ti49.2Ni50.8 single crystals oriented along [11] direction on the stress-induced B2-R-B19' thermoelastic martensitic transformations and superelasticity are investigated. It is experimentally established that aging at 823 K for 1h under compression stress of 150 MPa along [11] direction leads to the precipitation of one crystallographic variant of Ti3Ni4 particles of 350(±30) nm in size. Precipitation the single variant of Ti3Ni4 particle results in an appearance of homogeneous long-range internal stress field | | ≈ 65 MPa, that defines the main features of stress-induced B2-R-B19' transformation and determines the increase in the characteristic temperatures of martensitic transformation and the existence of two-way shape memory effect.