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| STUDY ON PARTITION RATIO AND SEGREGATION BEHAVIOR OF DZ125 ALLOY DURING DIRECTIONAL SOLIDIFICATION |
| Zhixian, SHEN Jun, FENG Zhourong, WANG Lingshui, LIU Lin, FU Hengzhi |
| State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 |
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Cite this article:
MIN Zhixian SHEN Jun FENG Zhourong WANG Lingshui LIU Lin FU Hengzhi. STUDY ON PARTITION RATIO AND SEGREGATION BEHAVIOR OF DZ125 ALLOY DURING DIRECTIONAL SOLIDIFICATION. Acta Metall Sin, 2010, 46(12): 1543-1548.
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Abstract Segregation behavior is an important problem in solidification process of alloys, which determines their growth morphologies, phase distributions and concentration segregations so that it affects the mechanical properties of alloys, such as fatigue lives, creep properies, etc.. However, the segregation behaviors of Ni–based superalloys are very complex that contain multi–components and consist of multi–phases. The solute partition coefficient is a key characteristic parameter to express the solute segregation level and tendency in a solidification process. In the present paper, the solute profiles in directionally solidified DZ125 alloy with planar interface growth, which was obtained through experiments of quenching during directional solidification, have been measured by electron probe micro analysis (EPMA). The steady state of solute redistribution hardly reaches due to melt flow during solidification process. The contents of γ′ phase forming elements, Al, Ti, Ta, Mo and Ni, along longitudinal direction increase with the increase of solidified fraction, while those of W, Cr and Co decrease. The results show that the solute prtition coefficients of Al, Ti, Ta, Mo and Ni are less than unit, those of W, Cr and Co are more than unit. In addition, the solute distribution in solid phase with dendrite growth is similar to that with planar interface growth. Compared the experimental rsults of microsegregation with the calculated ones of Scheil model and Brody–Flemings model, the Brody–Flmings model fits better with the experimental results. It indicates that the back–diffusion in solid phase would reduce the microsegregation during dendrite growth.
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Received: 28 June 2010
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| Fund: Supported by National Natural Science Foundation of China (No.50827102), National Basic Research Program of China (No.2010CB631202) and the Research Fund of State Key Laboratory of Solidification Processing (No.28–TP–2009) |
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