Al-Mg-Fe-Ni based alloy for high strain rate superplastic forming

A novel Al-Mg-Fe-Ni based alloy doped by Sc and Zr exhibits high strain rate superplasticity, good mechanical properties and corrosion resistance. The superplastic sheets of the alloy exhibit unrecrystallised grain structure after processing by a simple thermomechanical treatment and subsequent annealing at a temperature up to 0.97T(melt). Superplastic deformation behaviour for the given alloy was studied by performing tensile tests with constant strain rates in a range of 2 x 10(-3) - 1 x 10(-1) s(-1) and initial strain rates of 1 x 10(-2) and 1 x 10(-1) s(-1). The microstructure and the texture evolution of the studied alloy deformed at various constant strain rates were analysed by an SEM-EBSD method. The strain rate sensitivity index m approximate to 0.5 and elongation up to 750% were achieved due to the formation of a fine microstructure with a grain size of 2-4 mu m at superplastic deformation. The developed alloy exhibits superplasticity at the strain rates up to 1 x 10(-1) s(-1), the yield strength of 270 MPa and the ultimate tensile stress of 385 MPa.