http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1328 In situ neutron diffraction patterns were recorded from a 3Y-TZP sample during a complete loading–unloading cycle at compressive loads up to 2.3 GPa. The macroscopic stress–strain diagram shows elastic behavior to 1.7 GPa followed by volume conserving plastic strains of ~1.6 × 10⁻³. There were no signs of t→m transformation in the neutron diffraction patterns, and intensity changes in the pattern show that the plasticity is due to ferroelastic switching of tetragonal zirconia crystals. Quantification of the degree of switching gives good agreement with the macroscopic strains. The ferroelastic switching is completely reversed by a process akin to creep relaxation on unloading. Lattice parameters, elastic constants, and structural changes as a function of load are also discussed. 2010-04-27T06:55:22.957Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:368 The mechanical response of liquid nitrogen-quenched 9.4 Mg-PSZ in which the orthorhombic (o) phase is the major constituent (46 wt%) was investigated using in-situ neutron diffraction during uniaxial compression. The material remains elastic below 1 GPa with a Young's modulus of~242 GPa, second highest of all zirconia-based materials and highest of all zirconia-based ceramics. Beyond 1 GPa, the material develops small plastic strains in a time-dependent manner (i.e., by room temperature creep) although the strains were generally much smaller than the unquenched material, which contains no o phase. As for standard Mg-PSZ, the creep was accompanied by a volume change usually indicative of tetragonal to monoclinic (m) phase transformation; however, the amount of m phase apparent in the neutron diffraction patterns increased only marginally. The magnitude of the volume increase could not be accounted for by the observed increase in the m phase and hence, microcracking is believed to be responsible for most of the volume change. There is some evidence for a small amount of o to m transformation at the detection limit of the phase analysis technique. 2010-04-27T05:46:44.820Z ]]>