Exploring the elastic and electronic properties of chromium molybdenum diboride alloys

We perform first-principles calculations to study the structural, mechanical, thermal, electronic, and magnetic properties of Cr1-xMoxB2 for x = 0.25, 0.33, 0.50, 0.67 and 0.75. Based on structural search methods, we determine the ground-state structure for each concentration. The ternaries are either monoclinic (x = 0.25, 0.75) or trigonal (x = 0.33, 0.50, 0.67). The calculated mechanical properties reveal that the strength of Cr1-xMoxB2 is maximized for x = 0.50. Cr0.5Mo0.5B2 exhibits excellent mechanical properties (B = 298 GPa, Y = 558 GPa, G = 235 Gpa, nu = 0.19, H-v =27 GPa), surpassing those of beta-MoB2 at a lower cost. All of these ternaries are hard alloys with Vickers hardness greater than 24 GPa. Chemical bonding analysis demonstrates that the strength of the new compounds is related to the alternating planar and buckled B-B layers, as well as the strong TM-B bonds. The enhanced strength of Cr0.5Mo0.5B2 is a consequence of the high density of strong interlayer Cr-Mo metallic bonds around the Fermi level. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, first-principles calculations were used to investigate the properties of Cr1-xMoxB2 alloys, with Cr0.5Mo0.5B2 showing excellent mechanical properties at x=0.50. Chemical bonding analysis further confirmed the relationship between the strength of the new compounds and their structure and chemical bonds.