自生复合Cu08Cr合金定向凝固过程研究

A Study on Directional Solidification of In situ Cu 0 8Cr Alloy

研究了非平衡状态下Ｃｕ０８ｗｔ％ Ｃｒ 亚共晶合金的定向凝固过程。结果表明， 当温度梯度为３０℃／ｃｍ ， 生长速度分别为３μｍ ／ｓ 和３０μｍ ／ｓ 时， Ｃｕ０８ｗ ｔ％ Ｃｒ 合金呈（α枝晶＋ 共晶） 的非平衡凝固组织； 当温度梯度为３０℃／ｃｍ 时， α枝晶一次间距随生长速度的增大而增大， 这与枝晶一次间距的Ｈｕｎｔ模型在低速度段的规律一致， 而与ＫＰ模型的规律相反； Ｃｒ 纤维的形成主要与液态Ｃｒ 的表面张力、Ｃｒ 原子在液相中横向扩散能力及α枝晶间Ｃｒ 相的生长环境有关，增强Ｃｒ 原子的扩散能力，减小α枝晶侧向分枝及其间隙尺寸有助于规则Ｃｒ纤维的形成。

Directionally solidified procedure of the hypo eutectic alloy, Cu 0 8wt%Cr, under the status of non equilibrium solidification, was studied Results show that when the temperature gradient is 30℃/cm and the growth speed is 3μm/s and 30μm/s respectively, the microstructure of this alloy is a non stable one of α dendrite plus (α+β) eutectic; furthermore, the primary distance among α dendrites increases with the rise of the growth speed of dendrites This is in accordance with the varying rule of the primary dendritic distance within low speed period described by Hunt model, but contrary to that described by K F model Forming the Cr fibers depends on the surface tension of liquid Cr, the cross wise diffusion power of Cr atoms in liquid phase, and the growth environment for Cr phase between α dendrites So improving the diffusion of Cr, decreasing the lateral branch of α could help the formation of regular fibers of Cr