Rapid Solidification Processing and Powder Metallurgy of Al Alloys.
Annual rept. no. 2, 15 Apr 83-14 Apr 84,
ILLINOIS UNIV AT URBANA DEPT OF METALLURGY AND MINING ENGINEERING
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During the second year of the program, there have been five areas of emphasis. These are 1 the development of a model to describe the mechanism of formation of rapidly solidified Al alloys i.e. zones A and B ii the processing of particulate whose microstructure consists entirely of zone A iii the microstructures of rapidly solidified particulate of alloys based on Ai-8Fe iv the identification of metastable phases which form in some of the Al alloys studied and v dynamic compaction of particulate. A simple model for the formation of rapidly solidified hyper-eutectic Al alloys has been developed. This model is based on the degree of undercooling achieved prior to nucleation and the extent to which recalescence effects may be inhibited by a rapid rate of heat-extraction. Zone A microstructures form when the temperature is lowered to below that of the extended alpha-Al liquidus where primary Al may be nucleated. The microstructures of rapidly solidified Al-Ni and Al-Co alloys may be interpreted satisfactorily by this model.
- Properties of Metals and Alloys