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ABSTRACT The effect of transition elements, specifically Mn, Cr, V, and Mo, on dispersoid formation and mechanical properties in 6082 aluminum alloy was studied. The elevated-temperature mechanical properties were evaluated based on the compressive yield strength and creep resistance. The results indicated that the addition of Mn to the 6082 alloy resulted in the formation of a large number of the thermally stable α-Al(MnFe)Si dispersoids, thereby significantly improving the elevated-temperature mechanical properties of the alloy. Subsequent additions of Cr, V, and Mo increased the amount of Mn-bearing intermetallic phases, which decreased the supersaturation levels of Mn and Si in the α-Al, and consequently decreased the volume fraction of the dispersoids. The alloys containing Cr, V, and Mo exhibited similar yield strengths at 300°C and higher yield strengths at room temperature compared to the alloy containing only Mn. The size effect of the smaller dispersoids containing Cr, V, and Mo together with the solid-solution hardening of these elements could balance out the strength decrease resulting from the decreased volume fraction of the dispersoids. The additions of Cr, V, and Mo significantly increased the creep resistance of the Mn-containing 6082 alloy. Vanadium induced the highest creep resistance followed by Cr and Mo. Solute atoms of these elements with low diffusivity in the aluminum matrix contributed significantly to increasing the creep resistance at 300°C. 相似文献
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Y. Birol 《Journal of Thermal Analysis and Calorimetry》2008,93(3):977-981
DSC analysis is applied to investigate the precipitation reaction in the AA6005 extrusion alloy for different heat treatment
practices often presented in commercial production. The quenching practice is shown to have a big impact on the response of
the AA6005 alloy to an artificial ageing treatment. The range of β″ precipitation is displaced to lower temperatures in samples
quenched in air following the solution treatment. This acceleration, however, does not produce a favorable effect on age hardening
capacity since much of the solute Mg and Si is removed from the solid solution before the principal hardening phase can precipitate.
The DSC results are in good agreement with the age hardening curves. Natural ageing before artificial ageing promotes clustering
activities during a subsequent thermal exposure and produces a strong delay in β″ precipitation. 相似文献
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The elemental distribution of a precipitate cross section, situated in a lean Al-Mg-Si-Cu-Ag-Ge alloy, has been investigated in detail by electron energy loss spectroscopy (EELS) and aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). A correlative analysis of the EELS data is connected to the results and discussed in detail. The energy loss maps for all relevant elements were recorded simultaneously. The good spatial resolution allows elemental distribution to be evaluated, such as by correlation functions, in addition to being compared with the HAADF image.The fcc-Al lattice and the hexagonal Si-network within the precipitates were resolved by EELS. The combination of EELS and HAADF-STEM demonstrated that some atomic columns consist of mixed elements, a result that would be very uncertain based on one of the techniques alone. EELS elemental mapping combined with a correlative analysis have great potential for identification and quantification of small amounts of elements at the atomic scale. 相似文献
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In order to improve the mechanical properties and to optimize grain refinement of Al-Mg-Si alloy, ECAP processing with an addition of hard particle TiB2 is applied in this work. Mechanical property and microstructural evolution of Al-0.3Mg-7Si+1.5 wt.% TiB2 specimen were investigated by using hardness-testing, optical micrograph observation and electron-backscattering diffraction (EBSD). ECAP processing was done through BA route for 4 passes at room temperature. Hardness test results show that the ECAP process doubled the hardness of the specimen compared to annealed specimen, and from EBSD/OIM analysis, the ECAP processing refined grains from an average grain size of 35 μm to 0.79 μm and led to producing grains having high misorientation angle (≥15). 相似文献
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Y Birol 《Journal of Thermal Analysis and Calorimetry》2006,83(1):219-222
The deformation introduced
during the sample preparation had a high impact on the response of the alloy
AA6082 to heating in the DSC cell. The DSC curve was strikingly different
when DSC samples of this alloy were punched after the solution treatment.
Dislocations introduced by punching have annihilated the quenched-in vacancies
and have suppressed clustering initially. Dislocations have also provided
heterogeneous nucleation sites for the GP-1 zones that readily grew to become
stable nuclei for the β" phase owing to the enhanced atomic transport.
β" as well as the β' precipitation kinetics were thus accelerated
leading to a substantial change in the DSC peak arrangement. Deformation introduced
during sample preparation by gentle grinding alone, on the other hand, did
not suffice to alter the precipitation sequence, producing a DSC curve very
similar to that obtained with samples punched before the solution treatment. 相似文献
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