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Evolution of Metastable α 2 Phase in a Quenched High‐Nb‐Containing TiAl Alloy at 800 °C
Author(s) -
Wang Xuyang,
Yang Jieren,
Hu Rui,
Wu Yulun,
Fu Hengzhi
Publication year - 2020
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201901539
Subject(s) - materials science , equiaxed crystals , microstructure , alloy , metastability , annealing (glass) , recrystallization (geology) , phase (matter) , quenching (fluorescence) , crystallography , merge (version control) , r phase , metallurgy , analytical chemistry (journal) , martensite , optics , chemistry , paleontology , physics , organic chemistry , information retrieval , computer science , fluorescence , biology , chromatography
Fast cooling from high temperatures is a common way in heat treatments and hot processing, which could introduce excess metastable α 2 phase in the microstructure. Herein, the evolution of the metastable α 2 phase in a water‐quenched Ti–45Al–8.5Nb–(W, B, Y) alloy from different single‐phase regions is experimentally studied. After water quenching from the β single‐phase region, Widmanstätten α 2 , as well as residual β o , γ grains form from β phase and thin γ laths in α 2 phase are observed. However, the water‐quenched microstructure from the α single‐phase region consists of equiaxed α 2 grains, residual β o , and massive γ phase. When annealing the quenched samples at 800 °C, similar microstructural evolutions are found in both samples quenched from different temperatures. 1) α 2 phase transform into α 2 /γ nanolamellar structure immediately. 2) Recrystallization and discontinuous coarsening occur at the colony boundaries. 3) The nanometer‐scale γ/γ T lamellae transformed from α 2 grains are also unstable, which merge into thicker γ lamellae, and the interfaces of coarsened γ lamellae become curvy and blurry.