High-Temperature Deformation Behavior of the _γ Alloy Ti-48Ai-2Cr-2Nb

Abstract

The hot-workability of a two-phase (Y+l-2) alloy, Ti-48A1-2Cr-2Nb, has been studied by conducting isothermal compression tests to 0.8 true strain over the temperature range of 975-1200'C at strain rates between 1lxlO-1 and 3x10-3 s-1 . A deformation map showing temperature, strain rate, soundness of deformation, and isostress contours was constructed. Good workability is found from the low temperature/low strain rate regime to combinations of high temperature and either high or low strain rate. The upper-limit flow stress for good workability is between 450 and 500 MPa. Deformation induced softening occurs at all conditions. SEM and TEM examinations of the deformed specimens reveal that non-uniform deformation takes place at all strain rates, but cracking occurs mostly at high strain rates (e.g. 1x00-1 s-0), especially combined with low temperatures. The cracking appears to progress primarily along /o/a2 interfaces. It is thought that non-uniform deformation develops channels of shear bands, which in turn promote localized recrystallization, thus accommodating higher strains.

Hot deformation behavior of TiAl alloys prepared by blended elemental powders

“…Dynamic recrystallization is one of the restoration processes of PM TiAl alloys during hot deformation and it plays an important role in hot working, which is similar to cast TiAl alloys, for example, Seetharaman [19], Fujitsuna [20] and Shih [21] reported that the dynamically recrystallized structure was observed in cast Tie49.5Ale2.5Nbe1.1Mn, Tie47Ale1V and Tie48Ale2Cre2Nb alloys after deformation in the temperature range 1000e1200 C, although sometimes the recrystallization was incomplete for fully lamellar structure. Z.C.…”