Microstructural evolution during annealing of a powder metallurgical TiAl–Nb composite and its effect on mechanical properties

Microstructural, microhardness and electrochemical properties of heat-treated LENS in-situ synthesized Ti–Al-x(Mo, Si) alloys

“…The SEM measurements make it evident that Mo with 0.1 rpm resulted in microstructures with refined grains but the samples developed at 0.2 rpm Mo showed lager grained microstructures. Based on previous studies [ 42 , 54 ], it is evident that the as-built samples in Fig. 2 have near-gamma (NG) type microstructures.…”

“…This is caused by a rise in β o phase quantity, which is more soluble in Si than α 2 phase [ 37 ]. According to earlier research [ 42 , 62 ], phases of α/α 2 is usually precipitated within the lamellar to lower the nucleation energy barrier, thus keeping a distinct interaction with the γ matrix. The α and γ phases are thought to have a Blackburn orientation relationship, which is (0002)α || {111}γ, <1120>α || <110>γ [ 42 ].…”

“…According to earlier research [ 42 , 62 ], phases of α/α 2 is usually precipitated within the lamellar to lower the nucleation energy barrier, thus keeping a distinct interaction with the γ matrix. The α and γ phases are thought to have a Blackburn orientation relationship, which is (0002)α || {111}γ, <1120>α || <110>γ [ 42 ]. As a result, the α phase is thought to precipitate from the γ phase's {111} crystal planes in accordance with this orientation relationship.…”

“…The AM methods that have been successfully adopted for producing TiAl-based alloys are laser engineered net shaping (LENS), EBM and selective laser sintering (SLS) [ 3 , 9 , 32 ]. In 2006, AM was adopted by General Electric (GE: the world's biggest manufacturer of commercial aviation engines) to fabricate LPT blades of Boeing 777X GE9X engine [ 42 ] using a TiAl-based intermetallic alloy. Notwithstanding, the shortcomings TiAl-based intermetallic alloys is lack of formability and brittleness at RT that inhibits the extensive commercial use.…”

“…The likelihood of a novel light-weight TiAl alloy for marine structural applications, as well as the alloy's electrochemical corrosion and tribological behaviour in a saltwater environment, were examined by Cheng et al [ 45 ]. Ti44Al6Nb1Cr2V and Ti44Al6Nb1Cr2V0.15Y0.1B alloys were the subject of isothermal oxidation studies conducted by Gong et al [ 27 ] at 900 °C for 100 h. Lou et al [ 42 ] evaluated the microstructure developed by the composite after heat treatment and their influence on fracture and mechanical behaviours. They also carried out a simple heat treatment technique on PM composite of TiAl–Nb with nearly or entirely lamellar structures.…”