The effect of ultrafine grained microstructures on the hot-workability of intermetallic/ceramic composites based on γ-TiAl

Synthesis of an ultrafine grained TiAl based alloy by subzero temperature milling and HIP, its microstructure and mechanical properties

“…This study shows that the low temperature reactions in the Ti/Al based composite powders facilitated by the submicrometer and nanometer scaled reaction couples in the composite powder particles allow all the starting and intermediate phases to be converted into the equilibrium TiAl and Ti 3 Al phases by heating to temperatures in the range of 800-1000 • C. In the case of synthesizing ultrafine grained TiAl alloys from elemental powders, this is very important, because if the powder compacts have to be heated to well above 1000 • C to complete the required reactions, it would be very difficult to maintain ultrafine grains in the consolidated materials due to fast grain coarsening at temperatures greater than 1000 • C. Microstructural examination of the HIPed samples using TEM confirms that a nanocrystalline near-gamma TiAl structure is obtained by HIPing the Ti/Al composite powder at 800 • C, and the nanocrystalline structure is coarsened to an ultrafine microstructure (grain sizes less than 400 nm) when the HIP temperature is increased from 800 to 1000 • C. This is very much in line with the microstructural observation of TiAl based alloys by similar powder metallurgy route [8,9].…”

“…The room temperature ductility of TiAl based alloys can be improved by tailoring the microstructures of the alloys in terms of the volume fraction of the ␣ 2 -Ti 3 Al phase, and the structure and size of the lamellar colonies through heat treatment and composition modification [1,3,5,7]. It has also been demonstrated that refining near-gamma grains and/or the lamellar colonies is an effective way of improving the ductility and formability of the material [1,5,8,9].…”

Submicron-grained multiphase TiAlSi alloys: Processing, characterization, and microstructural design

“…51,52 With respect to advanced application properties in the high-temperture range, a selective grain coarsening of the ␥-TiAl phase would be highly desirable. 51,52 With respect to advanced application properties in the high-temperture range, a selective grain coarsening of the ␥-TiAl phase would be highly desirable.…”

Bulk Synthesis and Characterization of Ti3Al Nanoparticles by Flow‐Levitation Method

“…During recent years, many attempts have been made to improve the ductility. Attempts adapted include techniques such as grain refinement to nanoscale structure [4][5][6] and microstructure modification [7,8]. Thus research aiming to produce nanocrystalline materials by improved experimental techniques is relevant.…”