Effect of the Mass Fraction of NiTi–TiB(2) SHS-Particles on the Phase Composition, Structure, and Mechanical Properties of Inconel 625–NiTi–TiB(2) Composites Produced by Direct Laser Deposition

This paper studies the impact of the mass fraction of NiTi–TiB(2) particles obtained by the method of self-propagating high-temperature synthesis (SHS) on the phase composition, structure, and mechanical properties of composites made by direct laser deposition from an Inconel 625–NiTiz–TiB(2) powder mixture. Composites were obtained from a powder mixture with the mass fraction of particles at 5–10 wt%, and they consisted of an Inconel 625 metal matrix wherein ceramic inclusions of titanium diboride TiB(2) were distributed. Increasing the mass fraction of SHS-produced NiTi particles from 30 to 95 wt% led to the emergence of a NiTi intermetallide phase in the matrix material as well as an increase in the average TiB(2) particle size and formation of their agglomerates. In addition, an increase in the microhardness of the materials was observed. The graph of tensile strength of Inconel 625–NiTi–TiB(2) samples has a parabolic shape with a maximum at 1000 MPa (when the mass fraction of SHS-produced NiTi–TiB(2) particles is at 30 wt%). A further increase in the mass fraction of NiTi–TiB(2) led to a decrease in the tensile strength down to 400 MPa. Here the deformation of samples decreases linearly as the ratio of composite particles in the initial mixture increases. From a comparative analysis of the results obtained, the optimal mass fraction of composite NiTi–TiB(2) particles in the Inconel 625-NiTi–TiB(2) powder mixture was found to be 5 wt%.