Effects of Withdrawal Rate on the Microstructure of Directionally Solidified GH4720Li Superalloys
Increasing the ingot size of GH4720Li superalloys makes it difficult to control their microstructure, and the withdrawal rate is an important factor in controlling and refining the microstructure of GH4720Li superalloys. In this study, GH4720Li superalloy samples were prepared via Bridgman-type dire...
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doaj-8268b9338c504735bdfb0c318b3545b22020-11-25T02:49:38ZengMDPI AGMaterials1996-19442019-03-0112577110.3390/ma12050771ma12050771Effects of Withdrawal Rate on the Microstructure of Directionally Solidified GH4720Li SuperalloysJinglong Qu0Shufeng Yang1Zhengyang Chen2Jingshe Li3Anping Dong4Yu Gu5Beijing Central Iron and Steel Research Institute, Beijing 100081, ChinaSchool of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, ChinaSchool of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, ChinaSchool of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, ChinaSchool of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaBeijing Central Iron and Steel Research Institute, Beijing 100081, ChinaIncreasing the ingot size of GH4720Li superalloys makes it difficult to control their microstructure, and the withdrawal rate is an important factor in controlling and refining the microstructure of GH4720Li superalloys. In this study, GH4720Li superalloy samples were prepared via Bridgman-type directional solidification with different withdrawal rates. The morphology and average size of the dendrites in the stable growth zone during directional solidification in each sample, morphology and average size of the γ’ phases, and microsegregation of each alloying element were analyzed using optical microscopy, Photoshop, Image Pro Plus, field emission scanning electron microscopy, and electron probe microanalysis. Increasing the withdrawal rate significantly helped in refining the superalloy microstructure; the average secondary dendrite arm spacing decreased from 133 to 79 µm, whereas the average sizes of the γ’ phases in the dendrite arms and the interdendritic regions decreased from 1.02 and 2.15 µm to 0.69 and 1.26 µm, respectively. Moreover, the γ’ phase distribution became more uniform. The microsegregation of Al, Ti, Cr, and Co decreased with the increase in the withdrawal rate; the segregation coefficients of Al, Cr, and Co approached 1 at higher withdrawal rates, whereas that of Ti remained above 2.2 at all the withdrawal rates.http://www.mdpi.com/1996-1944/12/5/771withdrawal rateGH4720Limicrostructureaverage secondary dendrite arm spacingγ’ phasesegregation coefficient |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Jinglong Qu Shufeng Yang Zhengyang Chen Jingshe Li Anping Dong Yu Gu |
spellingShingle |
Jinglong Qu Shufeng Yang Zhengyang Chen Jingshe Li Anping Dong Yu Gu Effects of Withdrawal Rate on the Microstructure of Directionally Solidified GH4720Li Superalloys Materials withdrawal rate GH4720Li microstructure average secondary dendrite arm spacing γ’ phase segregation coefficient |
author_facet |
Jinglong Qu Shufeng Yang Zhengyang Chen Jingshe Li Anping Dong Yu Gu |
author_sort |
Jinglong Qu |
title |
Effects of Withdrawal Rate on the Microstructure of Directionally Solidified GH4720Li Superalloys |
title_short |
Effects of Withdrawal Rate on the Microstructure of Directionally Solidified GH4720Li Superalloys |
title_full |
Effects of Withdrawal Rate on the Microstructure of Directionally Solidified GH4720Li Superalloys |
title_fullStr |
Effects of Withdrawal Rate on the Microstructure of Directionally Solidified GH4720Li Superalloys |
title_full_unstemmed |
Effects of Withdrawal Rate on the Microstructure of Directionally Solidified GH4720Li Superalloys |
title_sort |
effects of withdrawal rate on the microstructure of directionally solidified gh4720li superalloys |
publisher |
MDPI AG |
series |
Materials |
issn |
1996-1944 |
publishDate |
2019-03-01 |
description |
Increasing the ingot size of GH4720Li superalloys makes it difficult to control their microstructure, and the withdrawal rate is an important factor in controlling and refining the microstructure of GH4720Li superalloys. In this study, GH4720Li superalloy samples were prepared via Bridgman-type directional solidification with different withdrawal rates. The morphology and average size of the dendrites in the stable growth zone during directional solidification in each sample, morphology and average size of the γ’ phases, and microsegregation of each alloying element were analyzed using optical microscopy, Photoshop, Image Pro Plus, field emission scanning electron microscopy, and electron probe microanalysis. Increasing the withdrawal rate significantly helped in refining the superalloy microstructure; the average secondary dendrite arm spacing decreased from 133 to 79 µm, whereas the average sizes of the γ’ phases in the dendrite arms and the interdendritic regions decreased from 1.02 and 2.15 µm to 0.69 and 1.26 µm, respectively. Moreover, the γ’ phase distribution became more uniform. The microsegregation of Al, Ti, Cr, and Co decreased with the increase in the withdrawal rate; the segregation coefficients of Al, Cr, and Co approached 1 at higher withdrawal rates, whereas that of Ti remained above 2.2 at all the withdrawal rates. |
topic |
withdrawal rate GH4720Li microstructure average secondary dendrite arm spacing γ’ phase segregation coefficient |
url |
http://www.mdpi.com/1996-1944/12/5/771 |
work_keys_str_mv |
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