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P.M. Kelly, L.R. Francis Rose/ Progress in Materials Science 47(2002)463-557 Nomenclature am, bm, cm crystallographic axes of monoclinic zirconia ao, bo, co crystallographic axes of orthorhombic zirconia crystallographic axes of tetragonal zirconia components of matrix used for transformation of axes the Bain strain -the strain required to convert one crystal structure to another tra Ion strain resistance to crack extension in martensite resistance to crack extension in austenite additional energy absorbed by stress-induced martensitic transformation per unit increase in crack length the magnitude of the lattice invariant shear 'L half height of the transformation zone(wake)surrounding a crack empirical parameter representing deviatoric component of overall transformation strain-see Eq (4.8) fracture toughness of material before transformation fracture toughness of material after transformation L the lattice invariant shear (LIS) in a martensitic transformation- normally slip or twinning net shear parameter-see Eq(4.10) rotation needed to make the undistorted plane in a martensitic transformation into an unrotated plane-i e. into the undistorted and unrotated habit plane the radius of an oblate spheroid of thickness 2t, where K<R he shape strain in a martensitic transformation. This consists of an invariant plane strain - a shear'y' together with a uniaxial expansion or contractions. Note that 5 must be equal to the volume change Av associated with the transformation the magnitude of the shape strainS stress assistance. SA= AUWORK -see Eq (4.11) elastic strain energy(per unit volume)of a martensite plate, usually in the form of an oblate spheroid of thickness ' and radius‘R deviatoric stre the semi-thickness of an oblate spheroid additional, small strain used by Hayakawa and Oka to "de-twin"the tetragonal domains in Y-TZP the dimensions 't' and'r' for a martensite nucleus of critical size volume fraction of particles or second phase ! $ + ) ! $ + ) ! $ + ) 5 $ + + F / D G + + ( $ HG ) 3H'G4 $ $ $ $ ;/ 31?4 . . 3,04 $ ' 6 $6 ;/ 31 "4 $ $6 $ " $ H!G ' " $ $ HG ' + +$ HG I / ( ' $ HG $ $ J AK ;/ 31 4 $ 3$ 4 $ $ HG H"G $ 5 ( $ -' K HH (' GG D(C " HG H"G ) ( $ $ ,- - . #-"- &! " / , $! ! 0 1 2)344 157