| In this study we have tried to fabricate nitride particle-reinforced composite materials through blowing nitrogen gas into Al-Li alloy melts, and identified the formation of nitride particles such as AlN and Li₃N. The average size of AlN and Li₃N dispersoids formed by nitriding reaction were a few ㎛ and nm order, respectively. The addition of Mg appeared to be effective to facilitate the nitriding reaction and to prevent the loss of Li due to deoxidation in the melt. And the tensile strengths of these N₂ gas-blowed composites were greatly increased compared to that of unblowed Al-Li alloy. Therefore it is clear that the formation of nitride particles had a great effect on the increase of tensile strength of the composites. However, long time blowing of more than 20 minutes resulted in a decrease of tensile strength due to the removal of preformed nitrides by the blowing gas. Ductility, which is a major problem of Al-Li alloys, is also greatly improved by this process compared to that of conventional Al-Li alloys. |
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