Study of grain boundary segregation using the Auger electron emission technique. Annual technical progress report, VII, January 1, 1977--December 31, 1977

Technical Report · Sat Jan 01 00:00:00 EST 1977

DOI:https://doi.org/10.2172/5257965· OSTI ID:5257965

Stein, D F; Heldt, L A; Clough, S P; Hack, J A; Pinchback, T R; Vonk, S J

An analysis of plastic flow at the tip of a propagating crack during brittle fracture has been developed. The plastic flow analysis takes into account the anisotropy of slip by a mixed mode opening scheme. Values of the true fracture energy for different crack systems are obtained; the effects of an embrittling agent can be taken into account. The fracture stresses of Cu--Bi alloys having varied grain sizes and Bi concentrations were measured. Dilute alloys exhibited a decreasing fracture stress with decreasing grain size. Auger analysis indicated a large variation of Bi segregated to boundaries in coarse grained materials with smaller variations in fine grained material. The grain boundary diffusion of nickel was studied in the Cu--Bi alloy system by means of Auger spectroscopy. Bi retards boundary diffusion of Ni; however, the results are quite complex since the Ni presence alters the Bi concentration at the boundary. The Bi concentration tends to decrease to a value approximately equal to that of Ni. Possible effects of solute segregation in determining SCC susceptibility of copper alloys in acid sulfate solution were examined with high purity binary alloys. Grain boundary segregation of Sb and Bi in Cu promoted intergranular SCC in sulfuric acid. Cracking was macroscopically brittle, but significant dissolution occurred along the intergranular crack path. Electrochemical measurements revealed an active path for SCC in segregated Cu--Sb and Cu--Bi alloys. Grain boundary segregation has no effect on the bulk electrochemical properties of unstressed Cu--Sb and Cu--Bi.

• Research Organization: Michigan Technological Univ., Houghton (USA). Dept. of Metallurgical Engineering
• DOE Contract Number: EY-76-S-02-2166
• OSTI ID: 5257965
• Report Number(s): COO-2166-24
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COPPER ALLOYS
CRACKS
GRAIN BOUNDARIES
AUGER ELECTRON SPECTROSCOPY
BISMUTH ADDITIONS
DIFFUSION
MATHEMATICAL MODELS
NICKEL ADDITIONS
PLASTICITY
SLIP
STRESS CORROSION
SULFURIC ACID
ALLOYS
BISMUTH ALLOYS
CHEMICAL REACTIONS
CORROSION
CRYSTAL STRUCTURE
ELECTRON SPECTROSCOPY
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NICKEL ALLOYS
SPECTROSCOPY
360102* - Metals & Alloys- Structure & Phase Studies