title: Colossal shear-strength enhancement of low-density cubic BC2N by nanoindentation.
abstract: Recently synthesized low-density cubic BC2N exhibits surprisingly high shear strength inferred by nanoindentation in stark contrast to its relatively low elastic moduli. We show by first-principles calculation that this intriguing phenomenon can be ascribed to a novel structural hardening mechanism due to the compressive stress beneath the indenter. It significantly strengthens the weak bonds connecting the shear planes, yielding a colossal enhancement in shear strength. The resulting biaxial stress state produces atomistic fracture modes qualitatively different from those under pure shear stress. These results provide the first consistent explanation for a variety of experiments on the low-density cubic BC2N phase across a large range of strain.
authors.affiliation: Department of Physics, Shanghai Jiao Tong University, Shanghai 200030, China.
authors.forename: Zicheng
authors.initials: Z
authors.lastname: Pan
authors.forename: Hong
authors.initials: H
authors.lastname: Sun
authors.forename: Changfeng
authors.initials: C
authors.lastname: Chen