Accession Number : AD0801341

Title :   A DOUBLE-LAYER MECHANISM FOR THE COMPLEX-ION EMBRITTLEMENT OF SILVER CHLORIDE.

Descriptive Note : Technical rept.,

Corporate Author : MARTIN MARIETTA CORP BALTIMORE MD RESEARCH INST FOR ADVANCED STUDIES

Personal Author(s) : Westwood, Albert R. C. ; Goldheim, David L. ; Pugh, Edison N.

Report Date : AUG 1966

Pagination or Media Count : 31

Abstract : A mechanism for the complex-ion embrittlement of AgCl is proposed which involves the adsorption-induced formation of charge double layers, initially at the surface, and subsequently ahead of propagating cracks. Since the predominant charge carriers in AgCl at room temperature are Frenkel defects, such double-layer regions will contain a high concentration of these defects. It is suggested that, under specific environmental conditions, the hardening resulting from their presence may be sufficient to cause surface embrittlement, and that failure may then occur by the repeated formation and rupture of such hardened layers. Experimental evidence in support of this hypothesis is presented. For example, the surface microhardness of AgCl is shown to be significantly increased when the specimen is immersed in an environment containing complexes of high charge. In addition, when polycrystalline specimens are stressed in such environments, the activation energy for the failure process over the temperature range 30 -100 C is in good agreement either with that for the motion of silver interstitials, or silver vacancies, depending on whether the sign of the charge on the adsorbing complexes is negative or positive, respectively. (Author)

Descriptors :   (*SILVER COMPOUNDS, CRYSTALLOGRAPHY), (*EMBRITTLEMENT, CHLORIDES), TENSILE PROPERTIES, STRESSES, HARDNESS, COMPLEX COMPOUNDS, SURFACE PROPERTIES, FAILURE(MECHANICS), TEMPERATURE, FRACTURE(MECHANICS), STATIC ELECTRICITY, HEAT OF ACTIVATION, CRYSTAL DEFECTS, SOLUTIONS(MIXTURES), NITRATES, CALCIUM COMPOUNDS, COPPER COMPOUNDS, SODIUM COMPOUNDS.

Subject Categories : Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE