Growth rate and composition of directionally solidified intermetallic TiAl–Nb alloys with different solidification conditions

作     者：Li-Wei Zhang Jun-Pin Lin Xiang-Jun Xu Jian-Ping He Xian-Fei Ding Xiao-Ou Jin 

作者机构：State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology Beijing Materials and Chemistry SchoolZhongyuan University of Technology National Center for Materials Service SafetyUniversity of Science and Technology Beijing School of Architecture and EngineeringHeilongjiang University 

出 版 物：《Rare Metals》 (稀有金属（英文版）)

年 卷 期：2016年第35卷第1期

页      面：54-64页

核心收录：

学科分类：08[工学] 0806[工学-冶金工程] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学] 0702[理学-物理学] 

基　　金：financially supported by the National Natural Science Foundation of China(Nos.51271016 and U1204508) the National Basic Research Program of China(No.2011CB605500) the Doctoral Program of Higher Education of China(No.20120006120042) the Fundamental Research Funds for the Central Universities(No.FRF-TP-14-062A2) 

主　　题：TiAl-Nb alloys Intermetallic Directionalsolidification Microstructural parameters Soluteconcentration 

摘      要：Intermetallic Ti-xAl-8Nb（x = 41,43,45,47,49;at%） alloys were solidified unidirectionally upwards with a constant temperature gradient of G=3.8 K·mm^（-1）at wide range of growth rates of v=10-400 μm·s^（-1）using a Bridgman directional solidification（DS） furnace.Microstructural parameters including the primary dendrite arm spacing（λ_1）,secondary dendrite arm spacing（λ_2）,dendrite tip radius（R） and mushy zone depth（d） were measured statistically.The values of λ_1,λ_2,R and d decrease as the growth rate increases for a given composition（x）.The values of λ_1,λ_2,R and v increase with the increase in x value,while the value of d firstly increases and then decreases with the increase in x value for a given v.The relationships between λ_1,λ_2 and R were analyzed by the linear regression.The average growth rate exponent of λ_1 is 0.29,which is in accordance with the previous experimental observations,and that of λ_2 is close to the previous experimental results,while those of R and d are lower than the results in other alloy systems.In addition,theoretical models for λ_1,λ_2 and R were compared with the experimental observations,and a comparison of the present experimental results with the theoretical models and previous experimental results was also made.