A P/M approach for the fabrication of an orthorhombic titanium aluminide for MMC applications

A study has been undertaken to examine the feasibility of using a powder me tallurgy (P/M) approach for the fabrication of an orthorhombic (O; Ti2AlNb) -based titanium aluminide alloy intended for use as a matrix in a continuou s fiber reinforced titanium matrix composite (TMC). Spherical powder of Ti- 22Al-26Nb (at%) was produced using inert gas atomization. The atomized powd er was sieved to -80 mesh (< 177 mu m) size fraction and used in the fabric ation of unreinforced "neat" panels via the tape casting process. Microstru ctural and phase chemistry examinations of the as-produced powder, thermall y exposed powder and neat matrix were conducted using back-scatter electron scanning electron microscope (BSE SEM) imaging, wavelength dispersive spec troscopy (WDS), and TEM analysis. Mechanical behavior studies of the as-fab ricated and heat treated neat material included: tensile, creep and isother mal fatigue. Results obtained for the P/M-based neat material were compared to previously obtained foil-based neat data, and to those property require ments necessary to be considered for use as a matrix in the fabrication of O TMCs. (C) 2000 Kluwer Academic Publishers.