等温热处理对Mg-6Zn-3Cu合金半固态组织演变的影响  

Effects of isothermal heat treatment on microstructural evolution of Mg-6Zn-3Cu alloy

作　　者：黄晓锋[1,2] 张玉[1] 秦牧岚 郝远[1,2] 

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,甘肃兰州730050 [2]兰州理工大学有色金属合金及加工教育部重点试验室,甘肃兰州730050

出　　处：《材料热处理学报》2016年第8期53-59,共7页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(51464032);国家973计划(2010CB635106)

摘　　要：通过半固态等温热处理,研究了重熔温度和保温时间对铸造ZC63镁合金半固态组织演变的影响。结果表明:半固态等温热处理能够将ZC63合金中的枝晶组织转变为球状组织,并可获得更加细小、分布均匀的球状颗粒;重熔温度和保温时间对非枝晶组织演变有着重要的影响,提高保温温度或延长保温时间,可加快原始铸锭重熔进程及组织形态的优化,保温温度过高或保温时间过长,试样会发生严重变形,同时球状颗粒易于粗化和长大;非枝晶组织演变是在熔化和结晶的动态变化中完成,主要的演变机制是在等温热处理过程中晶界处的共晶组织向基体溶解,原始组织的粗化、分离、球化以及球状颗粒的合并与长大。ZC63合金半固态触变成形最适合的等温热处理工艺是600℃×30 min。Effects of remelting temperature and holding time on microstructural evolution of as-cast ZC63 magnesium alloy were investigated by semi-solid isothermal heat treatment.The results show that the dendritic microstructure of the as-cast alloy can be transformed into spherical particles by semi-solid isothermal heat treatment,and finer,uniform distribution,more spherical particles are obtained.In addition,the remelting temperature and holding time have important effects on microstructural evolution of the alloy in isothermal temperature process.The increase of the remelting temperature or holding time can speed up the remelting process of original casting ingot and optimize microstructure.When the remelting temperature is too high or holding time is too long,the specimen presents severe deformation,meanwhile,the spherical particles easily coarsen and grow.The evolution of non-dendritic microstructure is completed by fusion and crystallization.The microstructural evolution mechanisms of the alloy during remelting are mainly composed of the dissolution of eutectic structures,the coarseness of initial microstructure,separation,spheroidization,combination and the growth of spherical particles.The optimal heat treatment parameters is reheating at 600 ℃ for 30 min for semi-solid thixoforming of the alloy.

关 键 词：ZC63镁合金 半固态等温热处理 非枝晶组织 演变机理 

分 类 号：TG146.22[一般工业技术—材料科学与工程]