SUPERPLASTICITY OF THE MG - CA EUTECTIC ALLOY
Superplastic flow is often associated with eutectic alloys having a microduplex structure, i.e. a two deformable phase structure with the grains of the two phases present on a micrometric scale and equiaxial shape. This particular morphology may be achieved by heavy hot deformation if the volume fraction of the eutectic second phase is sufficiently high to stabilize a fine grain size at elevated temperature. However, in the Mg - Ca eutectic alloy the superplastic flow has to be observed by the authors also starting with cast material if a large amount of tensile straining occurs. Initially the material is not superplastic and the deformation is localized to a neck. As a result the cast structure is converted by straining and dynamic recrystallisation to a microduplex structure and the necked zone is able to stretch 500 % or more. It then appeared evident that a prior ingot hot working would produce an initially superplastic material and this occurred in practice. The main results of experiments with both cast and hot worked Mg - Ca eutectic structures are reported here.
Bibliographic Reference: JOURNAL OF MATERIALS SCIENCE LETTERS, VOL. 3 (1984), PP. 60-64
Record Number: 1989123007100 / Last updated on: 1987-01-01
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