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

This paper studies the impact of the mass fraction of NiTi-TiB[sub.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[sub.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[sub.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[sub.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[sub.2] samples has a parabolic shape with a maximum at 1000 MPa (when the mass fraction of SHS-produced NiTi-TiB[sub.2] particles is at 30 wt%). A further increase in the mass fraction of NiTi-TiB[sub.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[sub.2] particles in the Inconel 625-NiTi-TiB[sub.2] powder mixture was found to be 5 wt%.