Spark plasma sintering of TiNiFeCoCux (X=0, 0.2) dual-phase high entropy alloy: Microstructural, mechanical and tribological characteristics

We synthesized Ti25Ni25Fe25Co25 and Ti20Ni20Fe20Co20Cu20 high entropy alloys using the mechanical alloying and spark plasma sintering (MA+SPS) method and examined their microstructural, mechanical, and tribological properties. The analysis revealed that the matrix structure comprises an FCC solid solution and C14 laves intermetallics. In the comparison of TiNiFeCo and TiNiFeCoCu samples, the mechanical characteristics diminished due to the presence of Cu in the TiNiFeCoCu alloy. The Vickers microhardness of the TiNiFeCo sample increased by similar to 43 %, nanohardness by similar to 157 %, and Young's modulus by similar to 24 % compared to the TiNiFeCoCu sample. The TiNiFeCo sample exhibited a reduced coefficient of friction (COF) and superior wear resistance compared to the TiNiFeCoCu sample. The yield strength and tensile strength of the TiNiFeCo sample rose by 53 % and 31 %, respectively, compared to the TiNiFeCoCu sample. The use of Cu in the TiNiFeCo composition resulted in a twofold increase in the ductility of the FCC matrix. The results demonstrate the substantial impact of Cu on the mechanical and tribological properties of the TiNiFeCo alloy. The presence of C14 laves hard intermetallic particles in the FCC high-entropy alloy microstructure led to dispersion strengthening, which was the primary factor in improving the overall strength and mechanical performance of the synthesized material.