Phase-field modelling of β(Ti) solidification in Ti-45at.%Al: columnar dendrite growth at various gravity levels

4th International Conference on Advances in Solidification Processes

材料科学;物理学

Viardin, A.^1 ; Berger, R.^1 ; Sturz, L.^1 ; Apel, M.^1 ; Hecht, U.^1

ACCESS E.V., Materials and Processes, Intzestr. 5, Aachen

D-52072, Germany^1

关键词: Columnar dendrites;    Convective effects;    Gamma titanium aluminides;    Macroscopic scale;    Phase field modelling;    Phase-field simulation;    Solutal convections;    Stable steady state;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/117/1/012007/pdf
DOI  :  10.1088/1757-899X/117/1/012007

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

The effect of solutal convection on the solidification of γ titanium aluminides, specifically on β(Ti) dendrite growth, is not well known. With the aim of supporting directional solidification experiments under hyper-gravity using a large diameter centrifuge, 2D-phase field simulations of β(Ti) dendrite growth have been performed for the binary alloy Ti-45at.%Al and various gravity scenarios. Both, the direction and magnitude of the gravity vector were varied systematically in order to reveal the subtle interplay between the convective flow pattern and mushy zone characteristics. In this presentation, gravity effects are discussed for early dendrite growth. For selected cases the evolution on longer timescales is also analyse of and oscillatory modes leading to dynamically stable steady state growth are outlined. In a dedicated simulation series forced flow is superimposed, as to mimic thermally driven fluid flow expected to establish on the macroscopic scale (sample size) in the centrifugal experiments. Above a certain threshold this flow turns dominant and precludes solutally driven convective effects.