Size-Dependent Structural Properties of a High-Nb TiAl Alloy Powder

Abstract

TiAl-based alloys are promising light weight structural materials for high temperature applications in the field of aerospace. Recently, fabrication technologies starting from powders including powder metallurgy and additive manufacturing have been developed to overcome the difficulties in the processing, machining and shaping of TiAl-based alloys. Spherical alloy powders with different particle size distributions are usually used in these fabrication techniques. The purpose of this study is to reveal the size-dependent structural properties of a high-Nb TiAl powder for these fabrication technologies starting from powders. A high-Nb TiAl pre-alloyed powder with nominal composition of Ti-48Al-2Cr-8Nb (at. %) was prepared by the electrode induction melting gas atomization (EIGA) method. The phase structure and morphology of the as-atomized powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The size-dependent structural changes of the as-atomized powders with different sizes were studied by differential scanning calorimetry (DSC) and in situ high temperature XRD. It was found that with decreasing the powder size, the content of the γ-TiAl phase decreases and the α2-Ti3Al phase increases. The α2-Ti3Al to γ-TiAl phase transformation was found in the temperature range of 600–770 °C. Based on the present work, the structural characteristics of TiAl powders are strongly dependent on their particle size, which should be considered in optimizing the process parameters of TiAl alloys fabricated from powders.

Spark Plasma Sintering of Titanium Aluminides: A Progress Review on Processing, Structure-Property Relations, Alloy Development and Challenges

“…Moreover, a cellular dendritic interior microstructure was observed, a characteristic microstructure of rapidly solidified metal droplets. In a related study, Liu and associates [28] studied the size-dependency on structural properties of a Ti-48Al-2Cr-8Nb (at. %) powder alloy produced using EIGA for PM and additive manufacturing technologies.…”

“…Voluntarily, a process control agent (PCA) is also added to aid in minimising cold welding and lump formation. Collisions between the wall of the Several studies involving the use of GA and SPS have been carried out to date [27][28][29][30]. Gu et al [27] fabricated pre-alloyed (PA) Ti-43Al-5Nb-2V-Y (at.…”

The Relationship between Microstructure and Fracture Behavior of TiAl/Ti2AlNb SPDB Joint with High Temperature Titanium Alloy Interlayers

“…With the advantages of low density, high melting point, and high specific strength, TiAl alloy has great potential in the field of aerospace. Numerous scholars have carried out studies on the processing methods and mechanical properties of TiAl-based alloys [ 1 , 2 , 3 , 4 ]. Cheng et al [ 5 ] studied the high-temperature deformation properties of a TiAl-based alloy and found that super-plasticity occurs—that is, when the temperature reaches 1000 ℃, the deformation mechanism of this alloy converted from the original dislocation slip and twinning to a grain boundary sliding mode.…”

Deformation and Phase Transformation of Disordered α Phase in the (α + γ) Two-Phase Region of a High-Nb TiAl Alloy

“…TiAl alloys are of great interest in high-temperature applications due to their low density, high specific strength, oxidation resistance, and good structural stability at high temperatures [1,2]. In recent years, research has shifted toward high-Nb TiAl alloys due to their higher service temperatures, which makes them attractive for replacing some Nibased superalloys in applications such as gas turbine engines [3][4][5].…”