| 總結: | This paper describes the as-sprayed microstructure of a model Al-4wt%Cu/SiC particulate (Al4Cu/SiCp) metal matrix composite (MMC) manufactured by spray forming, and the relationship between microstructure and solidification conditions during manufacture.Injection of SiCp, into the melt atomization region during the spray forming of A14Cu results in significant SiCp incorporation into molten droplets during atomization, and relatively little incorporation during flight to the substrate and at deposition. SiCp clustering is evident; in the A14Cu droplets and results in clustering in the as-sprayed MMC deposit.Matrix dislocation and precipitation microstructures are dependent upon local solidification conditions during spray forming, Increased dislocation density and increased quantity of fine-scale theta'-Al2Cu precipitation is found in the alpha-Al(Cu) matrix where local deposit cooling rates are high, i.e. in the vicinity of the substrate/deposit interface and when increased spray distances are used in manufacture. Lower dislocation density and increased quantity of grain-boundary theta-Al2Cu is found where deposit cooling rates are relatively low, i.e. distant from the substrate/ deposit interface and at decreased spray distances. In all cases, dislocation densities are higher in alpha-Al(Cu)/SiCp, interfacial regions than in the alpha-Al(Cu) matrix.There is no evidence of alpha-Al(Cu)/SiCp interfacial reaction in the as-sprayed condition indicating that cooling rates during spray forming are sufficiently rapid to prevent reaction.
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