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Deformation, recrystallization, strength, and fracture of press-forged ceramic crystals.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 Al2O3 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.-
Document ID
19720038251
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Rice, R. W.
(U.S. Navy, Naval Research Laboratory, Washington D.C., United States)
Date Acquired
August 6, 2013
Publication Date
February 1, 1972
Publication Information
Publication: American Ceramic Society
Subject Category
Materials, Nonmetallic
Accession Number
72A21917
Funding Number(s)
CONTRACT_GRANT: NAS7-276
Distribution Limits
Public
Copyright
Other

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