摘要
考察了Cu-1.7%Cr和Cu-5.6%Cr过共晶合金的定向凝固组织。实验表明:Cu-1.7%Cr和Cu-5.6%Cr过共晶合金定向凝固组织是由初生β相、α相和(α+β)共晶组成;α相是基于竞争生长机制的一种非平衡凝固组织。凝固速度和成分对初生β相生长形态产生显著影响。在Cu-1.7%Cr合金中,初生β相生长为等轴颗粒状,且受凝固速度的影响不大。在Cu-5.6%Cr合金中,随着凝固速度的增加,初生β相的生长形态经历了树枝状到等轴颗粒状的演变;α相包裹树枝状的初生β相生长,形成了类似"包晶"结构的微观形貌特征;颗粒状的、均匀分布的初生β相有利于α相的定向生长。降低合金成分和提高凝固速度有助于获得最佳组织形态的复合材料。
Microstructures of the hypereutectic Cu-1.7 % Or alloy and Cu-5.6 % Or alloy during the directional solidification were observed. The results show that the their microstructures consist of primary β phase, a phase and eutectic （α＋ β）. Based on the competitive growth mechanism, the α- phase is the non-equilibrium microstructure. The effect of solidification rates and element on the primary β-phase morphology are notable. The primary β phase in the hypereutectic Cu-1.7% Or alloy grow for the equiaxed particles. With the increase of solidification rates, the primary β phase in the hypereutectic Cu-5. 6% Or alloy undergo the evolution from the dendritic crystal to the equiaxed particles. The a phase develops around the dendritic β phase so that the microstructural morphology is parallel to the peritectic alloy. The uniform distribution of the equiaxed β-phase particles is propitious to the α-phase directional growth. Reducing the composition and improving the solidif.ication rate will help the composite material.
出处
《铸造技术》
CAS
北大核心
2009年第5期637-641,共5页
Foundry Technology
基金
河南省自然科学基金(0511052400)
关键词
过共晶
CU
CR合金
凝固特性
Hypereutectic
Cu-Or alloy
Solidification characteristics
