Published online by Cambridge University Press: 26 February 2011
A study has been undertaken to understand the cyclic deformation behavior of singlephase B2 aluminides. The alloys chosen for this study were rapidly solidified powder extrusions of Fe60 Al40 (at.%) and Ni50 A130 Fe20 (at.%). These alloys were chosen to compare the cyclic deformation behavior of a material that deforms by <111> slip and thus meets the von Mises criterion for slip system compatibility (Fe60Al40) with one that deforms by <100> slip and does not meet the von Mises criterion (Ni50A130Fe20). Fully reversed tension/compression tests were run in plastic strain control at room temperature. Rapid cyclic hardening was observed for the Fe60Al40 alloy. However, intergranular failure occurred before saturation was reached at all plastic strain amplitudes. The Ni50A130Fe20 alloy displays no tensile ductility , with failure occurring before completion of the first cycle. For the Ni50A130Fe20 alloy, a lower extrusion temperature during materials processing, and compressive prestrain both increase the cyclic accumulated plastic strain to failure, as well as the monotonic tensile ductility. This made cyclic deformation of the Ni50Al30Fe20 alloy possible. In this alloy, limited cyclic hardening is followed by saturation. For both the Fe60Al40 and Ni50 Al30Fe20 alloys, significant ductility enhancement was achieved by the application of thin nickel films. All cyclic deformation results are compared to similar monotonic tension results and are discussed in terms of the dislocation substructures observed.