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This research program was aimed at a detailed understanding of the effect of hydrogen as a temporary alloying element (thermohydrogen processing, THP) on processing parameters, microstructural modifications and final mechanical properties of cast- and-wrought (ingot metallurgy), powder metallurgy and cast titanium alloys. Fundamental results have been obtained which can now be used to develop optimum THP steps to refine the microstructure and improve the mechanical properties of titanium alloys. As a part of this project, the phase diagram of the Ti-6Al-4V - hydrogen system, and a determination of the stable and metastable phases, which occur in this system, have been defined. Kinetics of the beta phase decomposition has been studied and the non-equilibrium TTT (temperature-time-transformation) diagrams of the beta to alpha+beta+hydride transformation have been determined for the alloys with 10, 20, and 30 at.% hydrogen. Kinetics of decomposition of martensite structures have also been determined for these three hydrogen concentrations. The results have been presented at international meetings, twenty-two technical papers were published and twelve papers have been submitted for publication. Additionally a patent was also awarded. The results of the work have been transitioned to an Army SBIR program designed to produce low cost titanium components for armored vehicles.

Recent developments in powder metallurgy (P/M) processing techniques with emphasis on those 'far from equilibrium' processes which lead to enhanced mechanical and physical properties compared to conventional ingot metallurgy (I/M) approaches are reviewed. The text critically reviews the current and developing science/technology in the P/M field and the trends which are occurring. This should allow guidance to managers in their unenviable task of deciding where to put increasingly scarce research dollars. Amongst the facets of P/M synthesis/processing which offer the greatest future potential are fine powders (less than or equal to 1 micrometer), powder injection molding, mechanical alloying, vapor deposition, reactive processing, self-propagating high temperature synthesis, functionally graded materials, compaction with emphasis on reduced thermal exposures in combination with shape-making, metal matrix composites including recyclability issues, tool steels, joining, and modelling and real-time sensor control. The latter two aspects of the technology can broadly improve quality/reproducibility while leading to a cost-effective product. jg

This report covers the 7th World Conference on Titanium held in San Diego California, June 28 to July 2 1992. The purpose of the conference was to exchange information on advances in technology in titanium alloys, titanium processing, and applications of titanium alloys. Over 300 oral and 180 poster presentations were made by attendees from over 40 different countries including the former Soviet Union, Japan, China, and Europe. Total attendance was over- 700, which exceeded conference expectations., Prepared in cooperation with University of Idaho.