Processing and Consolidation of Nanocrystalline Cu-Zn-Ti-Fe-Cr High-Entropy Alloys via Mechanical Alloying

In the current investigation, nanocrystalline multicomponent high-entropy alloys (HEAs) have been synthesized in the CuxZnyTi20Fe20Cr20 system (x/y = 1/0, 3/1, 1; and x + y = 40) by mechanical alloying and subsequently consolidated using spark plasma sintering (SPS) in argon atmosphere at a pressure of 50 MPa. A detailed X-ray diffraction and transmission electron microscopy study reveals the presence of both FCC copper solid-solution, (Cu)ss and BCC chromium solid-solution, (Cr)ss phases in both the mechanically alloyed powders as well as the sintered compacts. The phase formation and stability of the sintered multicomponent CuxZnyTi20Fe20Cr20 with x/y = 3/1 and x + y = 40 pellet have been studied at different sintering temperatures, i.e., 873 K, 973 K, 1073 K, and 1173 K (600 °C, 700 °C, 800 °C, and 900 °C). The important findings include that high Vickers bulk hardness of around 6 GPa and relative density of around 95 pct reported in the CuxZnyTi20Fe20Cr20 with x/y = 3/1 and x + y = 40 HEAs, SPSed at 1173 K (900 °C). The formation, consolidation, and microstructural details are analyzed critically and discussed.