Abstract
Differential scanning calorimetry (DSC) in conjunction with transmission electron microscopy (TEM) are used to characterize the matrix precipitate structure of high strength and overaged tempers of three 7000 series aluminum alloys. Excellent consistency exists between the DSC results, based on the dissolution behavior of existing precipitates, and TEM observations. Comparison is made between matrix precipitate constituency and mechanical properties. A significantly high GP zone particle density was observed in a high strength 7050 alloy temper, but this temper did not have higher strength than other predominantly GP zone matrix tempers. Maximum strength was observed in a 7050 alloy temper that contained approximately equal amounts of GP zones and ή phase precipitates. Strengthening appears to be based on the contribution of both coherent GP zones and semicoherent ή precipitates. Use of the DSC approach and the free energy of activation for precipitate dissolution are recommended as rapid and quantitative means of precipitate identification.
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Adler, P.N., DeIasi, R. Calorimetric studies of 7000 series aluminum alloys: II. Comparison of 7075, 7050 and RX720 alloys. Metall Trans A 8, 1185–1190 (1977). https://doi.org/10.1007/BF02667404
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DOI: https://doi.org/10.1007/BF02667404