TY - JOUR
T1 - Microstructure evolution and nano-hardness modulation of rapidly solidified Ti–Al–Nb alloy
AU - Liang, C.
AU - Zhao, J. F.
AU - Chang, J.
AU - Wang, H. P.
N1 - Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/9/25
Y1 - 2020/9/25
N2 - Microstructure evolution, the formation of B2 (ordered BCC) phase and its relation to the nano-mechanical properties of the rapidly solidified Ti68Al32, Ti63Al32Nb5 and Ti58Al32Nb10 alloys were investigated by the drop tube technique. For the Ti68Al32 alloy droplets, the solidified microstructures are composed of α2-Ti3Al phase, when the droplet diameters (D) are ranging from 226 to 1100 μm. With the decrease of droplet diameters, the microstructural characteristics of α2 phase transform from coarse dendrites to the fully equiaxed grains. Notably, at D < 226 μm, the formation of α2 phase is suppressed, resulting in the retention of metastable α-Ti phase. For the Ti68-xAl32Nbx (x = 5, 10) alloys, the increasing of Nb contents promotes the formation of B2 phase and diminishes the size of the α2 grains. Upon further decreasing the droplet diameter, the microstructure evolves from dendrite dendrites to equiaxed dendrites, and the B2 phase precipitates from the core of α2 dendrites to α2 grain boundaries, which ascribes to Nb-segregation from the dendrite core area to the grain boundary via L→β and β→α, respectively. Nanoindentation test reveals that the hardness of α2 phase first increases and then decreases with the decrease of droplet diameters, which corresponds to the microstructure morphology, phase constitution, grain refinement of the alloys. Meanwhile, the additions of Nb exhibit enhanced properties of α2 phase compared with those with low or without Nb additions, which can effectively modulate the hardness of these alloys.
AB - Microstructure evolution, the formation of B2 (ordered BCC) phase and its relation to the nano-mechanical properties of the rapidly solidified Ti68Al32, Ti63Al32Nb5 and Ti58Al32Nb10 alloys were investigated by the drop tube technique. For the Ti68Al32 alloy droplets, the solidified microstructures are composed of α2-Ti3Al phase, when the droplet diameters (D) are ranging from 226 to 1100 μm. With the decrease of droplet diameters, the microstructural characteristics of α2 phase transform from coarse dendrites to the fully equiaxed grains. Notably, at D < 226 μm, the formation of α2 phase is suppressed, resulting in the retention of metastable α-Ti phase. For the Ti68-xAl32Nbx (x = 5, 10) alloys, the increasing of Nb contents promotes the formation of B2 phase and diminishes the size of the α2 grains. Upon further decreasing the droplet diameter, the microstructure evolves from dendrite dendrites to equiaxed dendrites, and the B2 phase precipitates from the core of α2 dendrites to α2 grain boundaries, which ascribes to Nb-segregation from the dendrite core area to the grain boundary via L→β and β→α, respectively. Nanoindentation test reveals that the hardness of α2 phase first increases and then decreases with the decrease of droplet diameters, which corresponds to the microstructure morphology, phase constitution, grain refinement of the alloys. Meanwhile, the additions of Nb exhibit enhanced properties of α2 phase compared with those with low or without Nb additions, which can effectively modulate the hardness of these alloys.
KW - Hardness
KW - Microstructure
KW - Phase transformation
KW - Rapid solidification
KW - Ti-Al-Nb alloys
KW - Undercooling
UR - http://www.scopus.com/inward/record.url?scp=85084504355&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2020.155538
DO - 10.1016/j.jallcom.2020.155538
M3 - 文章
AN - SCOPUS:85084504355
SN - 0925-8388
VL - 836
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
M1 - 155538
ER -