TY - JOUR
T1 - Microstructural characteristics of directionally solidified Ni-43Ti-4Al-2Nb-2Hf alloy
AU - Sang, Yurong
AU - Zheng, Lijing
AU - Pan, Qing
AU - Zhou, Lei
AU - Li, Yan
AU - Zhang, Hu
PY - 2011/3
Y1 - 2011/3
N2 - By liquid metal cooling (LMC) process, the Ni-43Ti-4Al-2Nb-2Hf (atomic fraction, %) alloy was directionally solidified (DS) at different casting temperatures (1350, 1450, 1550 °C) and a constant withdrawal rate of 6mm/min. Compared to the as-cast alloy, DS process has no effect on the phase composition, but significantly influences the phase morphologies. After DS, the NiTi phase preferentially grows along [100] orientation, and the macrostructure becomes the columnar crystals morphology with the [100] growth direction. Owing to the micro- segregation difference of Nb and Hf, the contrasts of primary NiTi phase become lighter from the center of dendrites to the edge. White Nb-rich Ti 2Ni phases distribute along growth direction in the light-contrast interdendritic regions, accompanied by Ti 2Ni precipitates. Actually, the finally solidified Ti 2Ni phase is the quasi-eutectic structure composed of Nb-rich Ti 2Ni and Ti 2Ni phase. The increases of casting temperature make the dendrites finer, also, Nb-rich Ti 2Ni more dispersively distributed.
AB - By liquid metal cooling (LMC) process, the Ni-43Ti-4Al-2Nb-2Hf (atomic fraction, %) alloy was directionally solidified (DS) at different casting temperatures (1350, 1450, 1550 °C) and a constant withdrawal rate of 6mm/min. Compared to the as-cast alloy, DS process has no effect on the phase composition, but significantly influences the phase morphologies. After DS, the NiTi phase preferentially grows along [100] orientation, and the macrostructure becomes the columnar crystals morphology with the [100] growth direction. Owing to the micro- segregation difference of Nb and Hf, the contrasts of primary NiTi phase become lighter from the center of dendrites to the edge. White Nb-rich Ti 2Ni phases distribute along growth direction in the light-contrast interdendritic regions, accompanied by Ti 2Ni precipitates. Actually, the finally solidified Ti 2Ni phase is the quasi-eutectic structure composed of Nb-rich Ti 2Ni and Ti 2Ni phase. The increases of casting temperature make the dendrites finer, also, Nb-rich Ti 2Ni more dispersively distributed.
KW - Casting temperature
KW - Directional solidification
KW - Intermetallics
KW - Microstructure
KW - NiTiAl alloy
UR - https://www.scopus.com/pages/publications/84862909325
U2 - 10.1007/s12598-011-0299-0
DO - 10.1007/s12598-011-0299-0
M3 - 文章
AN - SCOPUS:84862909325
SN - 1001-0521
VL - 30
SP - 340
EP - 344
JO - Rare Metals
JF - Rare Metals
IS - SUPPL.1
ER -