Nanoscale Precipitation Strengthening of the Al(Sc,Ti) Alloys

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This study investigated the precipitation strengthening of the binary Al-0.14wt% Sc, 0.16% Ti alloy system. Ingots of Al-2.1wt% Sc and Al-4.68wt% Ti were melted together, and the nucleation, growth, and coarsening of precipitates were analyzed. The microstructural evolution of the nanoscale L12 precipitates phase was examined with Vickers microhardness testing, transmission electron microscopy (TEM), and three-dimensional atom probe (3DAP). The chemical identities of the individual atoms, as well as the mechanical properties of the ternary alloy annealed at 300˚C for hours, were thus measured. Careful examination of the 3DAP data and the concentration profiles of the analyzed Al(Sc,Ti) alloy proved that the Ti partitioned and/or substituted into the Al3(Sc) precipitate. This Ti propagation decreased the lattice mismatch between the Al matrix and the Al3(Sc1-xTix) precipitates. This study attempted to determine if the partitioning of the Ti in the system would decrease the coarsening rate and increase the creep resistance properties of the alloy. Further analysis of the alloy at higher temperatures and longer aging times is required, however, since the microhardness values of the Al-0.14wt% Sc, 0.16% Ti were not considerably augmented in comparison with the Al-0.1wt% Sc binary two-phase alloy system previously studied. 

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  • 07/12/2018
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