Characteristics of cast Ti53.3-xNb10Zr10Ni10Co10Fe6.7Bx compositionally complex alloys

Abstract

Abstract In the current investigation, elemental boron was added to form a series of Ti53.3-xNb10Zr10Ni10Co10Fe6.7Bx 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. Ti48Nb10Zr10Ni10Co10Fe6.7B5.3 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.

Keywords

• TiNbZr compositionally complex alloys
• Boron
• Microstructure
• Hardness
• Wear resistance