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The microstructure and microhardness of a cast Al-10wt%Mg (henceforth Al-10Mg) alloy with 0.2wt% addition of Al-5Ti-0.25C master alloy were compared with those of a refiner-free alloy of similar chemical composition. It was found that this level ofthe master alloy addition not only caused an effective grain refinement, but also caused a significant increase in the microhardness ofthe Al-10Mg alloy. Microchemical analysis revealed that TiC particles existed in the grain center. The relationship between the holdingtime and grain size was also studied. It shows that the grain refining efficiency is faded observably with the holding time. This is ex-plained in terms of the instability of TiC particles.
The microstructure and microhardness of a cast Al-10wt% Mg (henceforth Al-10Mg) alloy with 0.2wt% addition of Al-5Ti-0.25C master alloy were compared with those of refiner-free alloy of similar chemical composition. It was found that this level of the master alloy addition not only caused an significant grain refinement, but also caused a significant increase in the microhardness of the Al-10Mg alloy. Microchemical analysis revealed that TiC particles existed in the grain center. The relationship between the holdingtime and grain This was ex-plained in terms of the instability of TiC particles.