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Deformation, Recrystallization, Strength, and Fracture of Press‐Forged Ceramic Crystals
Author(s) -
RICE ROY W.
Publication year - 1972
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.1151-2916.1972.tb11217.x
Subject(s) - materials science , recrystallization (geology) , crystallite , forging , grain boundary , ceramic , metallurgy , slip (aerodynamics) , composite material , microstructure , geology , paleontology , physics , thermodynamics
Sapphire and ruby were very difficult to press‐forge because they deformed without cracking only in a limited temperature range before they melted. Spinel crystals were somewhat easier and MgO, CaO, and TiC crystals much easier to forge. The degree of recrystallization that occurred during forging (which was related to the ease and type of slip intersections) varied from essentially zero in Al 2 O 3 to complete (i.e. random polycrystalline bodies were produced) in CaO. Forging of bi‐and polycrystalline bodies produced incoherent bodies as a result of grain‐boundary sliding. Strengths of the forged crystals were comparable to those of dense polycrystalline bodies of similar grain size. However, forged and recrystallized CaO crystals were ductile at lower temperatures than dense hot‐pressed CaO. This behavior is attributed to reduced grain‐boundary impurities and porosity. Fracture origins could be located, indicating that fracture in the CaO occurs internally as a result of surface work hardening caused by machining.