Indexed on: 01 Feb '89Published on: 01 Feb '89Published in: Journal of Materials Science
The rate sensitive flow characteristics in the elevated temperature deformation of Al-Fe-V-Si alloys processed by rapid solidification/powder metallurgy route were assessed by the strain rate change tests in compression. With an ultrafine grain size, stabilized by fine dispersoids, a peak rate sensitivity index of ∼0.15 and normal ductility were observed in alloys containing dispersoids up to a volume fraction of 0.37. The lack of superplastic response is interpreted in terms of a high threshold stress for superplastic flow. The threshold stress assessed by an extrapolation procedure is observed to be grain size and temperature dependent. Its origin is suggested to be Zener drag limited boundary migration, which is an essential part of the superplastic flow mechanism.