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Powder metallurgy (PM) of titanium is a potentially cost-effective alternative to conventional wrought titanium. This article examines both traditional and emerging technologies, including the production of powder, and the sintering, microstructure, and mechanical properties of PM Ti. The production methods of powder are classified into two categories: (1) powder that is produced as the product of extractive metallurgy processes, and (2) powder that is made from Ti sponge, ingot, mill products, or scrap. A new hydrogen-assisted magnesium reduction (HAMR) process is also discussed. The mechanical properties of Ti-6Al-4V produced using various PM processes are analyzed based on their dependence on unique microstructural features, oxygen content, porosity, and grain size. In particular, the fatigue properties of PM Ti-6Al-4V are examined as functions of microstructure. A hydrogen-enabled approach for microstructural engineering that can be used to produce PM Ti with wroughtlike microstructure and properties is also presented.

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Editor's Note: A hypertext-enhanced version of this article is available on-line at www.tms.org/pubs/journals/JOM/0405/Chandran-0405.html.Discontinuously reinforced titaniumtitanium boride whisker (TiB w ) composites are becoming a commercial reality for a number of demanding automotive, aerospace, and other advanced applications. This article presents the general microstructural characteristics and mechanical properties of Ti-TiB w composites of various matrix compositions and TiB w volume fractions based on the authors' research as well as work done elsewhere. The directions for future development in terms of the choice of titanium matrix compositions, microstructure control, and mechanical property optimization, as well as the realistic possibilities of near-term commercial applications in industry are discussed.

The design and performance of a novel in-situ electrochemical cell that greatly facilitates the neutron diffraction study of complex phase transitions in small volume electrodes of Li-ion cells, is presented in this work. Diffraction patterns that are Rietveld-refinable could be obtained simultaneously for all the electrodes, which demonstrates that the cell is best suited to explore electrode phase transitions driven by the lithiation and delithiation processes. This has been facilitated by the use of single crystal (100) Si sheets as casing material and the planar cell configuration, giving improved signal-to-noise ratio relative to other casing materials. The in-situ cell has also been designed for easy assembly and to facilitate rapid experiments. The effectiveness of cell is demonstrated by tracking the neutron diffraction patterns during the charging of graphite/LiCoO 2 and graphite/LiMn 2 O 4 cells. It is shown that good quality neutron diffraction data can be obtained and that most of the finer details of the phase transitions, and the associated changes in crystallographic parameters in these electrodes, can be captured.

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