半固态等温热处理对7075合金组织的影响  

Effect of Semi-solid Isothermal Heat Treatment on Microstructure of 7075 Alloy

作　　者：朱成 罗周梅 王瑞 赵志浩 ZHU Cheng;LUO Zhou-mei;WANG Rui;ZHAO Zhi-hao(School of Materials Science&Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学材料科学与工程学院,辽宁沈阳110819

出　　处：《东北大学学报（自然科学版）》2018年第12期1723-1726,共4页Journal of Northeastern University(Natural Science)

基　　金：辽宁省博士启动基金资助项目(20170520403);中央高校基本科研业务费专项资金资助项目/重大科技创新项目(N160212001)

摘　　要：研究了半固态等温热处理过程中,7075合金由枝晶组织转变为非枝晶组织的演变机理,并对比了半固态组织和铸态组织相组成的区别.结果表明,非枝晶组织的形成经过分枝特征的消失、晶界的平直化、晶界的弧状化与晶粒的长大3个阶段.其中,分枝特征的消失是由于位于二次枝晶臂的低熔点相熔化:部分液相团聚被包裹于固相颗粒内部;部分由枝晶通道流动至晶界处;另一部分液相与枝晶网格的边界处液相汇合,包裹着小固相颗粒. 7075铸态枝晶组织与半固态组织的组成相相同,都是由α-Al,η(MgZn2)和θ(Al2Cu)组成.Microstructure evolution of 7075 alloy from dendrite to non-dendrite during semi-solid isothermal heat treatment was studied and the difference of the phase constituents between as-cast and semi-solid microstructure was also investigated.The results show that the formation of non-dendritic structures has three stages:the disappearance of branching characteristics,flattening grain boundaries,arcuating grain boundary and grain growth.The disappearance of branching characteristics is caused by the melt of the low-melting-temperature phases located in the secondary dendrite arm:the agglomeration of part liquid phase wrapped inside the solid particles,some liquid phase flowed from the dendrite channels to the grain boundaries and the other liquid phase lapped together to form new solid particles.The phase constituents of both as-cast and semi-solid microstructures in 7075 alloys are allα-Al,η(MgZn 2)andθ(Al 2Cu).

关 键 词：半固态 等温热处理 7075合金 非枝晶 组织 

分 类 号：TG166.3[金属学及工艺—热处理]