Characteristics of cast Ti_53.3-xNb₁₀Zr₁₀Ni₁₀Co₁₀Fe_6.7B_x compositionally complex alloys

In the current investigation, elemental boron was added to form a series of Ti_53.3-xNb₁₀Zr₁₀Ni₁₀Co₁₀Fe_6.7B_x Compositionally Complex Alloys (CCAs). Alloying was done via vacuum arc melting in amounts of 0.0, 5.3, and 10.6 at.%. From the thermodynamic parameters, adding B to the base alloy increased the system's entropy. The microstructure of the prepared CCAs was characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction (XRD). The mechanical properties of CCAs as related to microstructure were assessed. According to XRD results, B-based intermetallic phases were obtained in the prepared CCAs, which were binary as Ti₃B₄ and ZrB₂ and ternary as FeNbB and Nb₃Co₄B₇. These intermetallic phases notably provided strengthening effects to the B-added alloys. Ti₄₈Nb₁₀Zr₁₀Ni₁₀Co₁₀Fe_6.7B_5.3 CCA showed the most homogenous microstructure obtained by the arc melting process. Adding B increased Young's modulus from 141 GPa (without B) to 195 GPa and 260 GPa with 5.3 and 10.6 at.%B, respectively. Hardness also increased from 502 to 606 HV with 5.3 at.% B and to 648 HV with 10.6 at.%B. Accordingly, the wear resistance increased with B addition where 10.6 at.%B sample showed the lowest wear rate among the other conditions. However, 5.3 at.% B was nominated as the optimum addition amount due to its notable microstructure homogeneity.