Sensitivity analysis of dendritic growth kinetics in a Bridgman furnace front tracking model

4th International Conference on Advances in Solidification Processes

材料科学;物理学

Mooney, R.P.^1 ; McFadden, S.^1

Trinity College Dublin, Dublin 2, Ireland^1

关键词: Columnar dendrites;    Columnar to equiaxed transition;    Dendritic growth;    Front-tracking models;    Growth parameters;    Microstructural transition;    Prediction criterions;    Solidification condition;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/117/1/012012/pdf
DOI  :  10.1088/1757-899X/117/1/012012

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

A directional solidification experiment of a Ti-Al-Nb-B-C alloy by power down method is simulated using a Bridgman furnace front tracking model. The effect of varying the dendritic growth parameters; C, the columnar dendrite growth coefficient, and n, the undercooling exponent, is investigated. A matrix of growth coefficients and undercooling exponents - at three levels each, based around a growth law for Ti-46wt.%Al - is applied in simulations, and the effect on columnar dendrite tip temperature, tip velocity, and tip temperature gradient is observed. The simulation results show that the dendrite tip velocity and temperature gradient at the tip are practically unaffected by the use of different growth parameters. However, the predicted columnar dendrite tip undercooling did vary to give the required dendrite tip velocity. This finding has implications for the analysis of microstructural transitions, such as the Columnar to Equiaxed Transition (CET). In conclusion, it is suggested that, for transient solidification conditions, a CET prediction criterion based on tip undercooling is preferable to one that uses growth velocity.