Probing the degenerate pattern growth of {100}《011 》 orientation in a directionally solidified A1-4.5 wt％ Cu alloy

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2019,（7）
• 页码范围: 1309-1314
• 页数: 6页
• 语种: 英文

摘要

Degenerate pattern is a seemingly disordered morphology but it exhibits the inherently ordered crystal connected with tip-splitting and limited stability which makes it difficult to observe in the metallic system.Here we employ (100)[011] orientated planar-front seeds using directional solidification and reveal the fundamental origins of the degenerate pattern growth in an A1-4.5 wt％ Cu alloy.We find that the spacing of the tip-splitting (λ) in the degenerate of the alloys followed a power law,λαV-0.5,and the frequency (f) of the splitting was related to the growth velocity (V) by fαV1.5.The dimensionless growth direction (θ/θ0) increased monotonously and approached 0.6 with faster velocity,attributed to its anisotropy in the interface kinetics.Once growth velocity exceeded a threshold,two types of pattern transitions from degenerate to regular dendrites were proposed.One of them exhibited a random and chaotic mode and the other underwent a rotation in growth direction.