PRELIMINARY STUDIES OF THE FABRICATION OF UAl 4 –Al TEST-PLATES BY POWDER-METALLURGICAL TECHNIQUES *

Abstract

The preparation of UAl₄ by induction melting and annealing (720°C, 993 K) yielded a product of restricted UAl₄ content (81 wt.-%). The UAl₄ phase has a variable stoichiometry (UAl_4.0–UAl_4.8), which leads to a slightly modified U–Al phase diagram. UAl₄–Al dispersions can be prepared by powder-metallurgical techniques, resulting in structures with higher UAl₄ content, improved phase-distribution rates, and specific particle sizes, compared with melting techniques. The thermal conductivity and thermal expansion of UAl₄–Al dispersions have been measured over the whole concentration range. No technological difficulties, by comparison with UAl₃-Al plate fabrication, were encountered. The production of UAl₄-Al test plates (33 vol.-% UA1₄ ≃ 35 wt.-% U) is thus feasible on a laboratory scale. The work reported is the final stage in a series of studies of uranium aluminide-aluminium dispersion fuels obtained by powder routes.