Microstructure Development of Directionally Solidified Nb-Ti-Si Based Ultrahigh Temperature Alloy  

作　　者：Guo Haisheng Guo Xiping Yao Chengfang 

机构地区：[1]State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi＇an 710072, China

出　　处：《稀有金属材料与工程》2009年第A03期24-27,共4页Rare Metal Materials and Engineering

基　　金：Supported by the National Natural Science Foundation of China (No 500671081) ;the Doctorate Foundation of Northwestern Polytechnical University (No CX200605)

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 (Nbss+(Nb,X)5Si3) eutectic colonies and a few hexagonally cross-sectioned (Nb,X)5Si3 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.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 CNbss＋（Nb,X）5Si3） eutectic colonies and a few hexagonally cross-sectioned （Nb,X）5Si3 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 1 μm/s, and the cellular solid/liquid interface formed when the withdrawing rate was 5 μm/s.

关 键 词：超高温合金 物理性能 热梯度 定向凝固组织 

分 类 号：TG146.416[一般工业技术—材料科学与工程]