Gamma-TiAl Intermetallics Processed by Field Assisted Hot Pressing: Analysis of the Temperature Effect on the Lamellar Microstructure Formation

摘要

A sintered γ-TiAl intermetallic alloy, Ti-45Al-2Nb-2Mn (at.%)-0.8vol.%TiB_2, has been processed from gas atomized prealloyed powder and field assisted hot pressing (FAHP). The processing technique consisted on passing high currents through a graphite die and punch set up which were placed inside the vacuum chamber of a Gleeble 3800 equipment. Therefore, the pressing and sintering of the powder were carried out in less than 20 minutes thereby obtaining samples with density values above 95%. Different temperatures were chosen in order to observe the effect of this parameter on the final microstructure. Duplex and nearly lamellar microstructures were obtained for the sintering temperatures of T ≥ 1000 °C, while not completely sintered samples and the presence of liquid phase were found at low temperatures (T < 1000 °C). From these results, a microstructure formation for this intermetallic alloy is proposed, as well as a new reproducible technique for the γ-TiAl manufacturing.