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Sinter‐Forging of Nanocrystalline Zirconia: II, Simulation
Author(s) -
Hague Douglas C.,
Mayo Merrilea J.
Publication year - 1999
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1999.tb01799.x
Subject(s) - forging , materials science , grain growth , nanocrystalline material , grain size , metallurgy , composite material , nanotechnology
A quantitative computer simulation of densification, pore‐size evolution, and grain growth during sinter‐forging has been developed and applied to the sinter‐forging of nanocrystalline yttria (30 mol%)‐stabilized zirconia (3Y‐TZP) at 1050° and 1100°C. Densification is simulated as a superposition of stress‐assisted and plastic‐strain‐controlled pore‐shrinkage mechanisms. Grain growth is simulated as a pore‐controlled process during intermediate‐stage densification and as a combination of normal (static) grain growth and dynamic grain growth during final‐stage densification. The densification portion of the model offers very good agreement with the experiment under a wide variety of imposed forging conditions, despite the absence of adjustable variables. Grain‐growth predictions qualitatively illustrate a key feature in the sinter‐forging of 3Y‐TZP: i.e., the minimization of grain size, as a function of density, under forging conditions that promote high strain rates. This particular effect seems to be due to the quick elimination of large pores by plastic strain while small pores (which shrink by diffusion) are still available to control grain growth.