title: Enhanced mechanical properties of nanocrystalline boron carbide by nanoporosity and interface phases.
abstract: Ceramics typically have very high hardness, but low toughness and plasticity. Besides intrinsic brittleness associated with rigid covalent or ionic bonds, porosity and interface phases are the foremost characteristics that lead to their failure at low stress levels in a brittle manner. Here we show that, in contrast to the conventional wisdom that these features are adverse factors in mechanical properties of ceramics, the compression strength, plasticity and toughness of nanocrystalline boron carbide can be noticeably improved by introducing nanoporosity and weak amorphous carbon at grain boundaries. Transmission electron microscopy reveals that the unusual nanosize effect arises from the deformation-induced elimination of nanoporosity mediated by grain boundary sliding with the assistance of the soft grain boundary phases. This study has important implications in developing high-performance ceramics with ultrahigh strength and enhanced plasticity and toughness.
authors.affiliation: WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Madhav Reddy
authors.forename: J J
authors.initials: JJ
authors.lastname: Guo
authors.forename: Y
authors.initials: Y
authors.lastname: Shinoda
authors.forename: T
authors.initials: T
authors.lastname: Fujita
authors.forename: A
authors.initials: A
authors.lastname: Hirata
authors.forename: J P
authors.initials: JP
authors.lastname: Singh
authors.forename: J W
authors.initials: JW
authors.lastname: McCauley
authors.forename: M W
authors.initials: MW
authors.lastname: Chen
mesh_terms: D001896:Boron Compounds / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D008422:Materials Testing; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology; D016062:Porosity; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D001896:Boron Compounds