In and ex situ investigations of the β-phase in a Nb and Mo containing γ-TiAl based alloy

Abstract

a b s t r a c tIn a b-stabilized Ti-43Al-4Nb-1Mo-0.1B alloy (composition in atomic percent) the correlation between the occurrence of b-phase and temperature was analyzed experimentally and compared to thermodynamic calculations. Results from in situ high-energy X-ray diffraction, texture measurements, heat treatments, scanning electron microscopy, and temperature-dependent flow stress measurements were used to study the evolution of the b-phase with temperature. Thermodynamic calculations based on the CALPHAD method were applied to correlate the phases developed in the b-solidifying TiAl based alloy under investigation. This alloy is characterized by an adjustable b-phase volume fraction at temperatures where hot-work processes such as forging and rolling are conducted. Due to a high volume fraction of bphase at elevated temperatures the hot-extruded alloy can be forged under near conventional conditions.

In situ study of dynamic recrystallization and hot deformation behavior of a multiphase titanium aluminide alloy

“…12 The disappearance of the ␥-TiAl phase determines the ␣-transus temperature which was determined as T ␣ = 1555 K in agreement with earlier reported values. 12,13 This good agreement provides convincing experimental evidence of the accuracy of the present experiment.…”

“…A more comprehensive account of TNM alloys is given by Clemens and co-workers. 9,10,13 The aim of the present study is to obtain in situ and in real time information from the bulk of the Ti-43.5Al-4Nb-1Mo-0.1B alloy during hot compression. The starting poly- crystalline microstructure consists of lamellar ␥ / ␣ 2 colonies with globular ␥-grains and ordered ␤ 0 -grains containing ␥-precipitates with a grain size of about 100 m. The recently developed high-energy synchrotron x-ray diffraction method 14 combined with the evaluation of the morphology of the diffraction Debye-Scherrer rings 15,16 is applied to a multiphase alloy undergoing hot plastic deformation.…”

In Situ Synchrotron Study of B19 Phase Formation in an Intermetallic γ‐TiAl Alloy

“…For further information on the role of β/β ophase in γ-TiAl based alloys, the reader is referred to. [4,5] To improve the understanding of the effects of Mo addition to γ-TiAl based alloys, an alloy with a nominal composition of Ti-45 Al-3 Mo-0.1 B (in at%) was produced. The phases occurring in this alloy were studied by means of in-situ high-energy X-ray diffraction (HEXRD) over a wide temperature range [6] and it was attempted to construct a phase diagram from the results of this study and information published in the literature.…”

In Situ Characterization Techniques Based on Synchrotron Radiation and Neutrons Applied for the Development of an Engineering Intermetallic Titanium Aluminide Alloy

“…As the γ phase does not disorder, the disappearance of its superstructure reflections implies its dissolution at T γ,solv . Thus, at 1275˝C, the material consists of the disordered phases α and β, as earlier work has proven for temperatures above 1300˝C [23]. Figure 6.…”