An Al-Mn-Fe-Si model alloy was subjected to two homogenization treatments, to achieve materials with different levels of Mn in solid solution and dispersoid densities, followed by cold rolling and back-annealing. Char...An Al-Mn-Fe-Si model alloy was subjected to two homogenization treatments, to achieve materials with different levels of Mn in solid solution and dispersoid densities, followed by cold rolling and back-annealing. Characterization of homogenization and deformation structures with respect to the effect of different microchemistries and strains on the structures was performed. Time-temperature-transformation （TTT） diagram with respect to precipitation and recrystallisation as a basis for analysis of the degree of concurrent precipitation was established. The TTT-diagram shows a strong effect of Mn concentration in solid solution and dispersoid density on the softening behavior. Recrystallization which finishes without the effect of concurrent precipitation results in an even, fine and equiaxed grain structure. Precipitation prior to or during recrystallization （concurrent） does retard the softening kinetics and leads to a coarse grain structure. However, the effect also depends on the duration of recrystallization and amount of precipitation. Recrystallization proceeding over a long time combined with a large amount of concurrent precipitation has a strong effect, otherwise the effect will be limited. Pre-existing fine and dense dispersoids （mean size 0.1 μm） before back-annealing do also lead to a coarse grain structure after recrystallization no matter whether additional concurrent precipitation occurs.展开更多
Two contents(1.5%and3%)of TiB2nanoparticles were introduced in Al?Mn?Mg3004alloy to study their effects on theelevated-temperature properties.Results show that TiB2nanoparticles were mainly distributed at the interden...Two contents(1.5%and3%)of TiB2nanoparticles were introduced in Al?Mn?Mg3004alloy to study their effects on theelevated-temperature properties.Results show that TiB2nanoparticles were mainly distributed at the interdendritic grain boundarieswith a size range of20?80nm,which is confirmed by transmission electron microscopy(TEM)and X-ray diffraction(XRD).Therefore,the volume fraction of the dispersoid free zones is greatly reduced and the motion of grain boundaries and dislocations isinhibited more effectively at elevated temperature.After peak precipitation heat treatment,the yield strengths in the alloy with3%TiB2addition at room temperature and300°C were increased by20%and13%respectively,while the minimum creep rate at300°Cwas reduced to only1/5of the base alloy free of TiB2,exhibiting a considerable improvement of elevated-temperature properties inAl?Mn?Mg alloys.展开更多
基金Project (KMB:193179/I40) supported by the Research Council of Norway
文摘An Al-Mn-Fe-Si model alloy was subjected to two homogenization treatments, to achieve materials with different levels of Mn in solid solution and dispersoid densities, followed by cold rolling and back-annealing. Characterization of homogenization and deformation structures with respect to the effect of different microchemistries and strains on the structures was performed. Time-temperature-transformation （TTT） diagram with respect to precipitation and recrystallisation as a basis for analysis of the degree of concurrent precipitation was established. The TTT-diagram shows a strong effect of Mn concentration in solid solution and dispersoid density on the softening behavior. Recrystallization which finishes without the effect of concurrent precipitation results in an even, fine and equiaxed grain structure. Precipitation prior to or during recrystallization （concurrent） does retard the softening kinetics and leads to a coarse grain structure. However, the effect also depends on the duration of recrystallization and amount of precipitation. Recrystallization proceeding over a long time combined with a large amount of concurrent precipitation has a strong effect, otherwise the effect will be limited. Pre-existing fine and dense dispersoids （mean size 0.1 μm） before back-annealing do also lead to a coarse grain structure after recrystallization no matter whether additional concurrent precipitation occurs.
基金support from the Natural Sciences and Engineering Research Council of Canada(NSERC)and Rio Tinto,through the NSERC Industry Research Chair in Metallurgy of Aluminum Transformation at University of Quebec at Chicoutimi
文摘Two contents(1.5%and3%)of TiB2nanoparticles were introduced in Al?Mn?Mg3004alloy to study their effects on theelevated-temperature properties.Results show that TiB2nanoparticles were mainly distributed at the interdendritic grain boundarieswith a size range of20?80nm,which is confirmed by transmission electron microscopy(TEM)and X-ray diffraction(XRD).Therefore,the volume fraction of the dispersoid free zones is greatly reduced and the motion of grain boundaries and dislocations isinhibited more effectively at elevated temperature.After peak precipitation heat treatment,the yield strengths in the alloy with3%TiB2addition at room temperature and300°C were increased by20%and13%respectively,while the minimum creep rate at300°Cwas reduced to only1/5of the base alloy free of TiB2,exhibiting a considerable improvement of elevated-temperature properties inAl?Mn?Mg alloys.
