Thermal stability of Al/Al11 Ce3 and Al/Al11 La3 /Al3 Ni eutectics obtained by Bridgman growth |
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Abstract: | AbstractThe effects of extended treatment at 500°C on microstructure and microhardness of Al/Al11 Ce3 and Al/Al11 La3 /Al3 Ni eutectics in Al–12·1Ce and Al–11·3La–5·4Ni (wt-%) alloys Bridgman solidified at 0·1 mm s-1 are reported. Coarsening of Al/Al11 Ce3 occurs more rapidly in some eutectic cells than others such that areas coarsening at a lower rate still form 10% of the microstructure even after 3024 h. It was found that Al/Al11 La3 /Al3 Ni showed accelerated coarsening at eutectic cell boundaries but association between Al11 La3 and Al3 Ni still remained within cells and at cell boundaries even after 3024 h. Associated decreases in hardness for Al/Al11 Ce3 were similar to fibrous Al/Al6 Fe of similar initial spacing subjected to the same heat treatment. The 30% higher initial hardness of Al/Al11 La3 /Al3 Ni largely persisted even after 3024 h at 500°C. |
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