过共晶Cu-Cr合金定向凝固组织中α相的形成机制研究  

Forming Mechanism of α-Phase in Directionally Solidified Microstructure of Hypereutectic Cu-Cr Alloy

作　　者：毕晓勤[1] 傅恒志[2] 

机构地区：[1]河南工业大学材料科学与工程学院,河南郑州450007 [2]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《铸造》2009年第7期710-712,716,共4页Foundry

基　　金：河南省自然科学基金(0511052400)

摘　　要：考察了Cu-1.7%Cr过共晶合金的定向凝固组织,对过共晶组织中出现亚共晶合金的初生α相的生长进行了探讨。研究表明:Cu-1.7%Cr过共晶合金定向凝固组织由初生β相、α相和(α+β)共晶组成;α相和(α+β)共晶的成分较大偏离平衡相图中的各相成分;初生β相分布在α相基体上。Cu-1.7%Cr凝固组织中α相的形成是非平衡凝固过程中枝晶α相和共晶相之间竞争生长的结果。α相是一种非平衡凝固组织,(α+β)共晶是偏离了平衡共晶成分的伪共晶组织。随着冷却速率的增加,α相的形貌尺寸减小,而数量有所增加。Microstructure of the hypereutectic Cu-1.7% Cr alloy during the directional solidification was observed, and the primary α-phase in the microstructure of the hypoeutectic Cu-Cr alloy that appeared in the microstructure of the hypereutectic Cu-Cr alloy was studied. The results show that the microstructures of the hypereutectic Cu-1.7%Cr alloy consist of primary β phase, α phase and eutectic （a＋β）. The components of α phase and eutectic （α＋β） deviate from the equilibrium composition of each phase in the phase diagram. The primary β phase distributes in the α-phase matrix. The formation of α-phase in the hypereutectic Cu-1.7% Cr alloy is the outcome of the competition growth between α dendritic and eutectic （ α＋β ） during the non-equilibrium solidification. The α-phase is the non-equilibrium microstructure and the eutectic （α＋β） is the pseudo-eutectic. With the increase of cooling rate, the α-phase refines and its number increases.

关 键 词：过共晶 CU-CR合金 定向凝固 机制 

分 类 号：TG131[一般工业技术—材料科学与工程]