Characteristic effects of alloying elements on β solidifying titanium aluminides: A review

Abstract

The high strength-to-weight ratio property of titanium aluminide (TiAl) based intermetallic alloys makes researchers regard this type of material as a potential replacement for the heavier superalloys of nickel. These alloys have been applied as turbocharger wheels of automobile and turbine blades of aircraft engines. A much recent alloy type of TiAl called the TNM alloy has emerged and primarily amenable to mechanical working; while providing the best combinations of mechanical properties that could be achieved through manufacturing processes with subsequent heat treatments. This is attained by solidifying entirely through the disordered β-phase (A2 structure). Effects of major alloying elements such as strength improvement, microstructural stability and phase formation demand the understanding of these alloying elements addition in TiAl-based intermetallic alloys. This review paper aims at encapsulating several works regarding the effects of major alloying elements on β-solidifying TiAl-based alloys and summarizing the characteristic effects of Si for these types of alloys. An impetus for future works on these types of intermetallic TiAl-based alloys is also presented.

Hot Corrosion and Oxidation Behaviour of TiAl Alloys during Fabrication by Laser Powder Bed Additive Manufacturing Process

“…Nb is one element used in many research works [86][87][88][89][90] to improve the oxidation resistance of TiAl alloys. Al activities are promoted by Nb additions and accelerate protective Al 2 O 3 oxide film formation, limiting oxygen diffusion into the alloy [166]. Also, the α 2 phase present in TiAl alloys is significantly decreased by Nb additions, decreasing its oxygen solubility [54].…”

Effect of growth rate on microstructure evolution in directionally solidified Ti–47Al alloy

“…The fully lamellar microstructure mainly consists of TiAl ( γ -phase) and Ti 3 Al ( α 2 -phase). The relative contents of these phases ( γ -phase) and ( α 2 -phase) can be controlled by adjusting the composition of the alloy [ 9 ]. In fully lamellar microstructure, the mechanical properties of TiAl-based alloys are strongly correlated to their lamellar orientation.…”

Modelling and simulation of the fatigue usage factor of γ-TiAl alloy fabricated through Laser Additive Manufacturing (LAM)

“…Intermetallic titanium aluminide-based (TiAl-based) alloys have fascinated researchers working in the automotive and aerospace industries owing to their properties such as excellent oxidation resistance, good elastic modulus, high strength, good creep resistance and most importantly low density (Raji et al 2019(Raji et al , 2020(Raji et al , 2021Verma et al 2017; Wang et al 2020). Nevertheless, TiAl alloys' ductility at ambient temperature is very poor, thereby limiting its production through wrought procedures like forging; while anisotropic mechanical properties are obtained for cast TiAl-based alloys due to coarse microstructures and unpredictable defects (Ismael and Wang, 2019; Raji et al 2020).…”