Mg-7Zn-0.3Mn-xCu镁合金半固态组织演变  

Semi-solid microstructure evolution of Mg-7Zn-0.3Mn-xCu alloy

作　　者：黄晓锋[1,2] 杨剑桥 魏浪浪 张乔乔 尚文涛 李旭娇 HUANG Xiao-feng;YANG Jian-qiao;WEI Lang-lang;ZHANG Qiao-qiao;SHANG Wen-tao;LI Xu-jiao(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China;Key Laboratory of Non-ferrous Metal Alloys and Processing,Ministry of Education,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,兰州730050 [2]兰州理工大学有色金属合金及加工教育部重点实验室,兰州730050

出　　处：《中国有色金属学报》2020年第6期1238-1248,共11页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(51464032)。

摘　　要：本文研究了Cu含量、重熔温度及等温时间对Mg-7Zn-0.3Mn镁合金半固态组织演变的影响。结果表明:Mg-7Zn-0.3Mn-1Cu合金的铸态组织由白色α-Mg基体和黑色共晶组织(α-Mg+Mg4Zn7+MgZn2+CuMnZn)组成。在等温热处理过程中,Cu有加速非枝晶颗粒分离和球化的作用,且Cu含量(质量分数)为1.0%时效果最佳;Mg-7Zn-0.3Mn-1Cu镁合金通过适当提高保温温度或延长保温时间,能够得到细小且分布均匀的球状颗粒。然而当保温温度超过585℃或保温时间超过20 min时,半固态颗粒则会粗化长大。这种粗化长大现象是在合并长大机制与Ostwald熟化机制共同作用下产生的。在整个等温热处理过程中,半固态组织演变主要经历了初始粗化、组织分离、球化和最后粗化四个阶段。Mg-7Zn-0.3Mn-1Cu镁合金的最佳等温热处理工艺参数为保温温度585℃和保温时间20 min,其非枝晶颗粒的平均尺寸、形状因子和固相率分别为38.85μm、1.39和53.38%。The effects of Cu content(0%,0.5%,1.0%,1.5%),remelting temperature and holding time on the evolution of semi-solid non-dendrites of Mg-7Zn-0.3Mn magnesium alloy were studied.The results show that the cast microstructure of the Mg-7Zn-0.3Mn-1Cu alloy is composed of whiteα-Mg matrix and black eutectic phase(α-Mg+Mg4Zn7+MgZn2+CuMnZn).And Cu accelerated the separation and spheroidization of non-dendritic particles during isothermal heat treatment,and the effect is optimal when the Cu content(mass fraction)is 1.0%.By properly raising the holding temperature or extending the holding time,Mg-7Zn-0.3Mn-1Cu can obtain finer and more uniform spherical particles.However,when the holding temperature exceeds 585℃or the holding time exceeds 20 min,semi-solid particles will gradually coarsene.This coarsening growth phenomenon is generated by the combined growth mechanism and Ostwald maturation mechanism.During the whole isothermal heat treatment process,the semi-solid microstructure evolution mainly experiences four stages:initial coarsening,tissue separation,spheroidization and final coarsening.The best parameters of isothermal heat treatment of Mg-7Zn-0.3Mn-1Cu are 585℃in holding temperature,20 min in holding time,and the average particle size,shape factor and solid fraction are 38.85μm,1.39 and 53.38%,respectively.

关 键 词：Mg-7Zn-0.3Mn-1Cu镁合金 CU含量 非枝晶组织 演变机理 

分 类 号：TG145.2[一般工业技术—材料科学与工程]