Microstructural Evolution and Stress Corrosion Cracking Behavior of AI-5083

摘要

The fine scale microstructure of Al-5083 (H-131) sensitized at 448 K (175 °C) for 1, 10, 25, 50, 100, 240, 500, and 1000 hours has been investigated using transmission electron microscopy (TEM) to study the evolution of the ? phase (Al_3Mg_2) at grain boundaries and on pre-existing intragranular particles. In fully sensitized Al-5083, the ? phase (Al_3Mg_2) forms heterogeneously both at grain boundaries and on pre-existing particles, which are enriched in manganese. TEM observations showed that the grain boundary precipitation of the fi phase initially occurs between 0 to 1 hour of aging at 448 K (175 °C), and that the fi phase grows with a ribbonlike morphology. The grain boundary planes are covered by the fi phase after 240 hours of aging. The contribution of microstructure, defects, and environment on the stress corrosion cracking (SCC) behavior is discussed.