Peculiarities of deformation and destruction of porous titanium nickelide alloys at stretching, compression and bending

Abstract

The analysis of experimental data obtained during quasi-static tension, compression and bending of anisotropic and structurally inhomogeneous porous titanium nickelide alloys obtained by the method of self-propagating high-temperature synthesis (SHS) is carried out. It is shown that the studied porous titanium nickelide alloy near room temperature is in a pre-martensitic state and experiences a reversible martensitic transformation (MT) under the action of an external load. The influence of geometric anisotropy on the deformation behavior under tension and bending is shown. By means of quasi-static tension and three-point bending to failure of lamellar samples of porous titanium nickelide with a porosity of 60-70%, it was shown for the first time that all obtained strain curves are qualitatively self-similar and contain a basic block of two linear hardening sections and a yield section between them. It is shown for the first time that a decrease in the effective cross section and a decrease in the degree of geometric anisotropy of the deformation zone lead to the appearance of an additional yield region on the deformation curves of quasi-static tension. This indicates a significant dependence of the contribution of reversible martensitic deformation to the total deformation on the geometric anisotropy of porous titanium nickelide. An analysis of fracture surfaces showed the effect of the type and rate of loading on the ratio of brittle martensitic and ductile austenite phases in a multiphase matrix of a porous titanium nickelide alloy.