Characterization of a solid solution of Cu in Al—Cu—SiCp metal matrix composites processed by spray atomization and co-deposition

Abstract

The effect of silicon carbide particulate (SiCp) reinforcement on the formation of a solid solution of copper (Cu) in Al–Cu alloys during spray atomization and co-deposition is investigated. The extent of Cu solid solubility in sample compositions of Al–1.3, 5.9 and 18.3 wt% Cu and Al–1.5, 5.9 and 19.4 wt% Cu+6 vol% SiCp was characterized using X-ray diffraction scanning electron microscopy, (SEM) microanalysis and high resolution electron microscope techniques. The copper content retained in the α-Al solid solution in Al-alloys both with and without SiCp additions was determined by initially deriving the lattice parameter (a) values of the samples by X-ray diffraction and the copper content in the solid solution was determined using a plot of a versus copper content previously, reported in the literature. Results of SEM microanalyses performed on the above alloys in regions of α-Al solid solution showed a good agreement on the amount of Cu retained in solid solution with values determined by X-ray diffraction especially for alloys containing small amounts of Cu. High resolution electron microscopy images of the matrix and the matrix/SiCp interface were employed in order to determine values of the interplanar spacing (d) for the α-Al solid solution and to correlate these values using the plot of lattice parameter as a function of copper content retained in solid solution. The results were in good agreement with those determined by the scanning electron microscopy microanalyses.