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Deformation and Fracture of Polycrystalline Lithium Fluoride
Author(s) -
SCOTT WILLIAM D.,
PASK JOSEPH A.
Publication year - 1963
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.1151-2916.1963.tb11728.x
Subject(s) - grain boundary , materials science , slip (aerodynamics) , crystallite , transgranular fracture , composite material , deformation (meteorology) , intergranular corrosion , plasticity , intergranular fracture , crystallography , metallurgy , corrosion , microstructure , chemistry , physics , thermodynamics
Techniques for the fabrication of polycrystalline LiF test specimens were developed and evaluated using single‐crystal LiF as a control. An etch was developed which revealed dislocations on all crystallographic faces of LiF. Large‐grained polycrystalline specimens tested in four‐point loading underwent 0.076 to 0.798% plastic strain before fracture. In most cases their yield stress was similar to that for single crystals favorably oriented for flow on {110}〈110〉 slip systems. Deformation was inhomogeneous among the grains because of differences in orientation with respect to the applied stress and within individual grains because of interactions at grain boundaries. Grain boundaries were barriers to slip, but stresses resulting from slip in one grain were transmitted to neighboring grains and often caused local deformation near the boundary. In one case, local boundary slip occurred on an (010) plane. Three‐grain junctions were areas of high residual stresses, and fractures originated at boundaries at or near three‐grain junctions. Fractures were mixed transgranular and intergranular.