title: Large increase in fracture resistance of stishovite with crack extension less than one micrometer.
abstract: The development of strong, tough, and damage-tolerant ceramics requires nano/microstructure design to utilize toughening mechanisms operating at different length scales. The toughening mechanisms so far known are effective in micro-scale, then, they require the crack extension of more than a few micrometers to increase the fracture resistance. Here, we developed a micro-mechanical test method using micro-cantilever beam specimens to determine the very early part of resistance-curve of nanocrystalline SiO2 stishovite, which exhibited fracture-induced amorphization. We revealed that this novel toughening mechanism was effective even at length scale of nanometer due to narrow transformation zone width of a few tens of nanometers and large dilatational strain (from 60 to 95%) associated with the transition of crystal to amorphous state. This testing method will be a powerful tool to search for toughening mechanisms that may operate at nanoscale for attaining both reliability and strength of structural materials.
authors.affiliation: Secure Materials Center, Materials and Structures Laboratory, Tokyo Institute of Technology, R3-23 4259 Nagatsuta, Midori, Yokohama, 226-8503, Japan.
authors.forename: Kimiko
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Secure Materials Center, Materials and Structures Laboratory, Tokyo Institute of Technology, R3-23 4259 Nagatsuta, Midori, Yokohama, 226-8503, Japan.
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Wakai
authors.affiliation: 1] Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany [2] Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0075, Japan.
authors.forename: Norimasa
authors.initials: N
authors.lastname: Nishiyama
authors.affiliation: Secure Materials Center, Materials and Structures Laboratory, Tokyo Institute of Technology, R3-23 4259 Nagatsuta, Midori, Yokohama, 226-8503, Japan.
authors.forename: Risako
authors.initials: R
authors.lastname: Sekine
authors.affiliation: Secure Materials Center, Materials and Structures Laboratory, Tokyo Institute of Technology, R3-23 4259 Nagatsuta, Midori, Yokohama, 226-8503, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shinoda
authors.affiliation: Secure Materials Center, Materials and Structures Laboratory, Tokyo Institute of Technology, R3-23 4259 Nagatsuta, Midori, Yokohama, 226-8503, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Akatsu
authors.affiliation: Precision and Intelligence Laboratory, Tokyo Institute of Technology, R2-35 4259 Nagatsuta, Midori, Yokohama, 226-8503, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagoshi
authors.affiliation: Precision and Intelligence Laboratory, Tokyo Institute of Technology, R2-35 4259 Nagatsuta, Midori, Yokohama, 226-8503, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Sone