The Mechanism of Liquid-Metal Embrittlement-Crack Growth in Aluminum Single Crystals and Other Metals in Liquid-Metal Environments.
Abstract
Metallographic and fractographic studies of fracture in single crystals of aluminum and zinc, and in polycrystalline aluminum, cadmium and tin in liquid-metal environments and in air are described. The commonly suggested mechanism for liquid-metal embrittlement--that chemisorption of liquid-metal atoms facilitates tensile rupture of stressed interatomic bonds at crack tips--is not supported by the present observations. Rather, observations of extensive slip around crack tips and dimpled fracture surfaces suggest that crack growth in embrittling liquid-metal environments occurs by plastic flow, but with considerably less blunting occurring at crack tips than in air. It is proposed that liquid-metal embrittlement can be explained on the basis that chemisorption of liquid-metal atoms facilitates the nucleation of dislocations at crack tips. Such an effect would produce sub-critical crack growth, change the distribution of slip around cracks and reduce the extent of blunting at crack tips, but would not generally influence bulk flow characteristics. The relevance of these results to hydrogen-embrittlement, stress-corrosion cracking, and ductile versus brittle behaviour in general is discussed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1977
- Accession Number
- ADA047010
Entities
People
- S. P. Lynch