Microstructure Development of Directionally Solidified Nb-Ti-Si Based Ultrahigh Temperature Alloy
来源期刊：稀有金属材料与工程2009年增刊第3期
论文作者：Guo Haisheng Guo Xiping Yao Chengfang
关键词：integrally directional solidification; Nb-Ti-Si based ultrahigh temperature alloy; directionally solidified microstructure; microstructural evolution;
摘 要：Integrally directional solidification of an Nb-Ti-Si based ultrahigh temperature alloy was performed in an ultrahigh temperature and high thermal gradient furnace with the use of ceramic crucibles. The microstructural evolution with the withdrawing rate increasing during directional solidification was revealed. The integrally directionally solidified microstructure was composed of couple grown lamellar (Nb_(ss)+(Nb,X)_5Si_3) eutectic colonies and a few hexagonally cross-sectioned (Nb,X)_5Si_3 columns (X represents Ti and Hf elements). All the directionally solidified microstructure was straightly aligned along the longitudinal axis of the specimens. With increasing of the withdrawing rate, the average diameter of the eutectic cells and inter lamella spacings in the eutectic cell decreased. The near-planar solid/liquid interface appeared when the withdrawing rate was 1μm/s, and the cellular solid/liquid interface formed when the withdrawing rate was 5 μm/s.
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摘要:Integrally directional solidification of an Nb-Ti-Si based ultrahigh temperature alloy was performed in an ultrahigh temperature and high thermal gradient furnace with the use of ceramic crucibles. The microstructural evolution with the withdrawing rate increasing during directional solidification was revealed. The integrally directionally solidified microstructure was composed of couple grown lamellar (Nb_(ss)+(Nb,X)_5Si_3) eutectic colonies and a few hexagonally cross-sectioned (Nb,X)_5Si_3 columns (X represents Ti and Hf elements). All the directionally solidified microstructure was straightly aligned along the longitudinal axis of the specimens. With increasing of the withdrawing rate, the average diameter of the eutectic cells and inter lamella spacings in the eutectic cell decreased. The near-planar solid/liquid interface appeared when the withdrawing rate was 1μm/s, and the cellular solid/liquid interface formed when the withdrawing rate was 5 μm/s.
关键词:integrally directional solidification; Nb-Ti-Si based ultrahigh temperature alloy; directionally solidified microstructure; microstructural evolution;
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