Viscoelastic deformation and destruction of porous nickelid titanium during tension and cyclic bend

The paper presents the experimental results of deformation dependences and fatigue tests of a porous nickelide titanium alloy obtained by the self-propagating high-temperature synthesis (SHS - TiNi). The deformation dependences obtained in the mode of stretching and three-point bending of porous plates have shown that porous samples undergo viscoelastic deformation due to the austenite - martensite phase transformation (A → M). Microscopic studies of fracture surfaces revealed areas of quasibrittle fracture of martensite and viscous fracture of austenite. The brittle nature of the destruction of non-metallic inclusions and the shell covering the porous framework of the intermetallic alloy is established. Successful fatigue strength tests have shown that brittle phases and inclusions do not have a critical negative effect on the deformation and fatigue characteristics of porous nickelide titanium. It was found that 70% of porous samples withstand 10⁶ cycles of deformation without fracture due to reversible phase transformations A → M → A in the TiNi phase, which is one of the components of a multiphase porous alloy.

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