Improved formability of aluminum--germanium near eutectic compositions through the application of superplasticity principles

The 80-20 and 70-30 atomic percent Al-Ge compositions, which are used in the Nb3(Al,Ge) superconducting material, were investigated. These alloys are brittle at room temperature, but have been deformed plastically in this study by simulating conditions that have produced superplasticity in similar materials. The microstructure of these Al-Ge compositions was controlled to produce an inherently ductile structure of Ge spheroids dispersed throughout an Al matrix. A very fast cooling rate followed by a short anneal of 7 minutes at 4000C has been found to produce a fine homogenous spheroidal structure in 0.5'' diameter castings. Vickers microhardness tests were performed on castings of lamellar and fibrous microstructures after anneals at temperatures from 300 to 4000C. The deformation behavior of castings subjected to various conditions is reported. Parameters such as microstructure, temperature, % reduction, and anneals were investigated, and the results were used to successfully reduce Al-Ge castings to wire