Development of Ultra-Fine Microstructure in Titanium via Powder Metallurgy for Improved Ductility and Strength
In an effort to produce an ultra-fine alpha titanium equiaxed grain structure, suitable for superplastic deformation processes, Armstrong-Process CP Ti powder, was consolidated into compacts with grain-size on the order of 2 to 3 microns. This powder has very fine dendritic-shaped particles with an inherent sub-micron grain-structure. In order to preserve as much as possible the fine powder microstructural scale, the compaction was accomplished by rapid-heating and short-hold VHP, using a procedure derived from a processing technique originally developed at the University of Dayton for producing nano-phase hard permanent magnets. It was modified to suit the titanium powder, and a range of parameters was experimented to produce a variation of microstructures. One set of compaction conditions resulted in the desired microstructure, and subsequent tensile testing demonstrated strength and ductility exceeding CP Ti Grade 3, due to the ultra-fine equiaxed alpha grain structure. The paper will discuss the various microstructures and the potential applications.
Marcello Cabibbo and Stefano Spigarelli
D. Eylon et al., "Development of Ultra-Fine Microstructure in Titanium via Powder Metallurgy for Improved Ductility and Strength", Materials Science Forum, Vols. 604-605, pp. 223-228, 2009