| Infiltration behavior of the molten metal, microstructure and mechanical properties of the SiC particulate reinforced Al alloy composites fabricated by pressureless infiltration technique have been studied. Under the nitrogen atmosphere the spontaneous infiltration of the molten Al alloy into the bed of powder mixture of Al, Mg and SiC occurred at relatively lower temperatures, compared with the infiltration of Al alloy into the bed of only SiC powder. Both Al₄C₃ and Si may be formed even at 700℃ as a result of the interfacial reaction between molten Al alloy and SiC, and the extent of reaction increased with an increase in temperature. As that Si is incorporated with Mg, the age hardening can occur during the precipitation of Mg₂Si. At 700℃ of a relatively low temperature, the extent of age hardening was small and/or the hardening rate was slow. The peak hardness during aging tends to slightly increase with increasing infiltration temperature. Tensile strengths of the specimens where Al-(0-6)Mg alloys infiltrated into the bed of powder mixture containing 3Mg exibited similar values but decreased in the case of the infiltration of Al-10Mg alloy. Also, the phenomenon that tensile strength of specimen infiltrated at 1000℃ of a high infiltration temperature decreased may imply the severe interfacial reaction. MgAl₂O₄ and Al₄C₃ formed as a result of the interfacial reaction between molten Al alloys and SiC were identified. |
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