COMPOSITION LIMITS OF THE SHAPE-MEMORY GAMMA-PHASE IN THE SYSTEM FE-MN-AL-SI

The maximum solubility limits of the fee gamma-phase adjacent to the ( gamma + alpha) and (gamma + beta-Mn) two phase regions and the (gamma + alpha + beta-Mn) three phase region of the Fe-Mn-Al system were dete rmined by optical microscopy. X-ray diffraction and mechanical propert ies. The effect of 1-4wt% Si additions on the location of the phase bo undary between the gamma-phase and the (gamma + beta-Mn) two phase reg ion has also been determined for compositions of Fe-30Mn-Al and Fe-35M n-Al containing 1-9 wt% Al, The shape memory effect in gamma-phase all oys in the quaternary system Fe-Mn-Al-Si was found to be relatively sm all, with a maximum recovery of 17.4% observed at a composition Fe-30M n-lAl-4Si. (C) 1997.