Transmission electron microscopy analysis of grain boundary precipitate-free-zones (PFZs) in an AlCuSiGe alloy

• Autores: Tolley, Alfredo Juan; Mitlin, D.; Radmilovic, V.; Dahmen, U.
• Año de publicación: 2005
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Aluminum alloy design; Transmission electron microscopy (TEM); Solid state precipitation
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

We have characterized the elevated temperature (190 ◦C) precipitation sequence near the grain boundaries of an AlCuSiGe alloy, comparing these results to the binary AlCu and the ternary AlSiGe. In the quaternary alloy, there is a graded microstructure that evolves with increasing distance from the boundaries, which is generally a superposition of the precipitate-free-zones (PFZs) in the binary AlCu and in the ternary AlSiGe. After aging for 3 h, this graded area consists of an approximately 140 nm wide region that is entirely precipitate free, followed by a 400 nm wide region that is denuded of Si–Ge and precipitates. Rather than containing the (Si–Ge)– pairs observed in the bulk, this 400 nm wide region contains only homogeneously nucleated . Only in the overaged condition (144 h) are the near grain boundary replaced by a coarse distribution of large plate-like . In the alloys, the solute depleted zones are much narrower than the total length of the PFZ. For example, in both AlCu and AlCuSiGe, the Cu depleted zone is only 30 nm wide. This underscores the need for vacancies during precipitation of not only and Si–Ge, but of as well.
Fil: Tolley, Alfredo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. University of California; Estados Unidos
Fil: Mitlin, D.. University of Alberta; Canadá
Fil: Radmilovic, V.. University of California; Estados Unidos
Fil: Dahmen, U.. University of California; Estados Unidos