Affiliation:
1. Materials Department, College of Engineering, University of California Santa BarbaraSanta Barbara, CA 93106-5050, USA
Abstract
This article investigates the toughness of yttria-stabilized zirconia (YSZ) with the tetragonal-prime (
t
′) structure. Such materials are used as durable thermal barriers in gas turbines. Their durability has been attributed to high toughness, relative to materials in the cubic phase field. Based on prior literature, a ferroelastic toughening mechanism is hypothesized and this assertion is examined by characterizing the material in the wake of an indentation-induced crack. Assessment by transmission electron microscopy, Raman spectroscopy and optical interferometry has affirmed the existence of a process zone, approximately 3 μm in width, containing a high density of nano-scale domains, with equal proportions of all three crystallographic variants. Outside the zone, individual grains contain a single variant (no domains) implying that the toughening mechanism is controlled by domain
nucleation
(rather than the
motion
of pre-existing twin boundaries). The viability of the ferroelastic toughening mechanism is assessed using a process zone model that relates the observed toughening to the stress/strain hysteresis accompanying domain formation. Based on the measured process zone size, the known tetragonality of
t
′-7 wt% YSZ and the enhancement in toughness relative to cubic YSZ, consistency between the model and the observed toughening is demonstrated for a reasonable choice of the coercive stress.
Subject
General Physics and Astronomy,General Engineering,General Mathematics
Cited by
229 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献