Superplastic behavior of spray-deposited 5083 Al

A 5083 Al alloy was synthesized using spray deposition processing with N-2 as the atomization gas. It was noted that the grains that were present in as-spray-deposited 5083 Al were equiaxed with an average size of 15.2 mu m. The matrix of the material was supersaturated with Mg and Mn. The as spray-deposited microstructure contained irregular pores with porosity in the range of 0.1 to 5.4 vol pct, depending on spatial location in the preform. The spray-deposited alloy was thermomechanically processed using extrusion and multiple-pass warm rolling to reduce grain size and close porosity. It was observed that spray-deposited 5083 Al exhibited superplasticity following thermomechanical processing by extrusion followed by rolling. Superplasticity was observed in the 500 degrees C to 550 degrees C temperature range and 3 x 10(-5) to 3 x 10(-3) s(-1) strain rate range. The corresponding strain-rate sensitivity factors were in the 0.25 to 0.5 range and increased with decreasing strain rate. A maximum elongation of 465 pct was noted at 550 degrees C and 3 x 10(-5) s(-1). The spray-deposited 5083 Al, thermomechanically processed by direct rolling, exhibited superplasticity in the same temperature and strain rate ranges as those for the extruded and rolled materials. The superplastic elongation of the spray-formed and rolled material was relatively low, being in the range of 250 to 300 pct. The deformation behavior is discussed in light of the presence of porosity in the microstructure.