Densification and deformation in the presence of a liquid phase

Technical Report · Sun Jul 01 04:00:00 EDT 1984

OSTI ID:6276700

Marion, II, J E

The mechanisms for creep and sintering of solid materials in the presence of a liquid phase are explored. In Part 1, the sintering behavior of a simple ceramic/glass system is studied. Densification involves concurrent viscous flow and solution/reprecipitation processes for which equations are proposed. Comparison of these equations with microstructural observations suggests that thin equilibrium grain boundary films can support gradients in normal stresses required for diffusive matter transport through the liquid. Evidence is presented for the existence of significant structure within the thin grain boundary films. The final stage in the liquid-phase sintering process, the closure of pores, is modeled using an extreme value distribution to describe the sizes of the shrinking pores. In Part 2, the investigation focuses on high temperature deformation in the presence of a liquid phase. At low stress levels, continuous deformation, without failure, is possible by matter transport through the liquid phase. At higher local stress levels, cavities form within the liquid and permit more rapid deformation leading to eventual failure. TEM results on creep damage in several liquid-phase sintered ceramic alloys exposed to creep strains at elevated temperatures are used to propose a sequence for the early stages of cavitation damage. Interface failure time models are generated for each step. Equations are derived for the growth and coalescence times for oblate holes in thin glass films along two grain interfaces. Times for formation of spherical holes along three grain channel glass pockets and growth to full-facet sized cavities are evaluated.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6276700
• Report Number(s): LBL-18411; ON: DE85005101
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
CAVITATION
CERAMICS
CREEP
DAMAGE
DEFORMATION
FABRICATION
FLUIDS
GLASS
LIQUIDS
MATERIALS
MECHANICAL PROPERTIES
POROSITY
SINTERED MATERIALS
SINTERING
SOLIDS