Atomistic observation of in situ fractured surfaces at a V-doped WC[sbnd]Co interface

• Published in: Journal of materials science & technology 2022-05, Vol.110, p.103-108
• Main Authors: Xiang, Congying, Shen, Min, Hu, Chongze, Wong, Lok Wing, Nie, Hongbo, Lei, Huasheng, Luo, Jian, Zhao, Jiong, Yu, Zhiyang
• Format: Article
• Language: English
• Subjects: Cemented carbide; Crack propagation; Fracture behavior; In situ observation
• ISSN: 1005-0302; 1941-1162
• DOI: 10.1016/j.jmst.2021.09.021

•Crack propagation dynamic across a V-doped WCCo interface is studied in TEM.•Aberration-corrected STEM is used to examine the as-fractured surface.•The fracture propagates between the V-containing trilayers and the abutting cobalt.•A loss of interfacial coherency accounts for the selected propagation path. An in situ mechanical test was performed on a V-doped WCCo specimen in a transmission electron microscope (TEM) to understand the crack propagation dynamics. The fracture occurs along a WCCo interface. Aberration-corrected high-angle annular dark-field (HAADF) imaging and energy-dispersive X-ray spectroscopy (EDS) mapping are combined to investigate the as-fractured surface. The interfacial cleavage plane is atomically flat, taking place between the V-containing trilayers and the abutting cobalt grain. No noticeable structural or compositional change is detected for the trilayer superstructure coherent with the underneath WC grain. Density functional theory (DFT) calculations reveal that the interlayer bonding within the coherent interfacial trilayer superstructure is strong while that between the superstructure and cobalt is substantially weaker due to incoherency. This study provides insights into the interfacial fracture behavior in hard metals and suggests the importance of interfacial coherency to fracture resistance.