Growth rate and composition of directionally solidified intermetallic TiAl–Nb alloys with different solidification conditions
来源期刊：Rare Metals2016年第1期
论文作者：Li-Wei Zhang Jun-Pin Lin Xiang-Jun Xu Jian-Ping He Xian-Fei Ding Xiao-Ou Jin
文章页码：54 - 64
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-1at wide range of growth rates of v=10-400 μm·s-1using a Bridgman directional solidification（DS） furnace.Microstructural parameters including the primary dendrite arm spacing（λ1）,secondary dendrite arm spacing（λ2）,dendrite tip radius（R） and mushy zone depth（d） were measured statistically.The values of λ1,λ2,R and d decrease as the growth rate increases for a given composition（x）.The values of λ1,λ2,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 λ1,λ2 and R were analyzed by the linear regression.The average growth rate exponent of λ1 is 0.29,which is in accordance with the previous experimental observations,and that of λ2 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 λ1,λ2 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.
Li-Wei Zhang1，Jun-Pin Lin1，Xiang-Jun Xu2，Jian-Ping He1，Xian-Fei Ding3，Xiao-Ou Jin4
1. State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing2. Materials and Chemistry School,Zhongyuan University of Technology3. National Center for Materials Service Safety,University of Science and Technology Beijing4. School of Architecture and Engineering,Heilongjiang University
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-1at wide range of growth rates of v=10-400 μm·s-1using a Bridgman directional solidification（DS） furnace.Microstructural parameters including the primary dendrite arm spacing（λ1）,secondary dendrite arm spacing（λ2）,dendrite tip radius（R） and mushy zone depth（d） were measured statistically.The values of λ1,λ2,R and d decrease as the growth rate increases for a given composition（x）.The values of λ1,λ2,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 λ1,λ2 and R were analyzed by the linear regression.The average growth rate exponent of λ1 is 0.29,which is in accordance with the previous experimental observations,and that of λ2 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 λ1,λ2 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.
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