Failure mode, ferroelastic behavior and toughening effect of bismuth titanate ferroelectric ceramics under uniaxial compression load. (15th August 2018)

• Record Type: Journal Article
• Authors: Chen, Yu; Xu, Jiageng; Xie, Shaoxiong; Nie, Rui; Yuan, Jing; Wang, Qingyuan; Zhu, Jianguo
• Is Part Of: Materials & design. Volume 152(2018)
• Page Start: 54
• Page End: 64
• Publication Date: 2018-08-15
• Subjects: Bi4Ti3O12 ceramics -- Ferroelastic domain switching -- Microcracks -- Compression load -- Toughening effect; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2018.04.055
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: A typic BLSF ceramics: bismuth titanate (Bi4 Ti3 O12 ), whose failure mode, ferroelastic behavior and toughening effect under uniaxial compression load were comprehensively assessed. Firstly, a series of crystallographic parameters including lattice constants ( a, b, c and v ), orthorhombicity ( g ) and single-crystal distortion ( S 0 lattice ) were calculated from XRD patterns. The ferroelastic behavior referred to the 90° switching of domains with compression stress was identified by the nonlinear stress-strain curve, and the underlying micromechanism was more accurately described by the non-180° domain wall motion. SEM observation on the fracture surface of the broken sample reveals its failure mode in terms of microcrack initiation and propagation behaviors. Further, a simplified domain distribution model was constructed for unpoled ferroelectric ceramics based on a constitutive framework, which deduced their constitutive relation subjected to uniaxial compression load. The ferroelasticity induced toughening was verified by indentation test, and further analyzed by a micromechanics model of crack propagation. The expression of toughening effect (Δ Г / Г ) was also deduced from the indentation fracture mechanics. Finally, the evolution in mechanical properties (including coercive stress ( σ c ), switching strain (εzz ), apparent elastic modulus ( E ) and compression strength ( σ cf )) of Bi4 Ti3 O12 ceramics with the doping content of W was also quantified by the compression test. Graphical abstract: Unlabelled Image Highlights: Two types of microcracks (opening and closed) initiated in the matrix of Bi4 Ti3 O12 ceramic during mechanical loading. The underlying micromechanism of ferroelastic domain switching was described by the non-180 o domain wall motion. The constitutive relation of ceramics under uniaxial compression load was obtained by a domain distribution model. The expression of ferroelasticity induced toughening effect (Δ Г / Г ) was deduced from the indentation fracture mechanics.