Research on Synthesis of High-Strength Aluminum Alloys. Part I. The Relation Between Precipitate Microstructure and Mechanical Properties in Aluminum Alloys,
BATTELLE COLUMBUS LABS OHIO
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The effects of the various small, intermediate, and large precipitates on the fracture toughness and fatigue properties of aluminum alloys based on the 2024 and 7075 compositions were studied. Different concentrations and sizes of the precipitates were obtained by systematic variations in the chemical composition and also in the homogenization and aging treatments. The roles of the various precipitates in deformation and fracture were determined by slip-line and fractographic studies, and these results were carefully correlated with the fracture toughness data. The dispersion hardening effect of the intermediate precipitates appeared to have only a minor effect on the fracture toughness of both alloys, but the intermediate precipitates did exert a major indirect effect on the fracture toughness of the 7000-series specimens because of their effect on recrystallization and grain size. As expected, the large precipitates formed during ingot solidification were detrimental to both alloys. The fatigue properties of the 2000-series alloys appeared to be relatively insensitive to the range of metallurgical variables investigated, but significant improvements were obtained in the 7000-series specimens.
- Properties of Metals and Alloys