Microstructure control of AZ31 alloy by self-inoculation method for semisolid rheocasting  

自孕育法制备AZ31镁合金半固态流变成形组织(英文)

作　　者：邢博[1] 郝远[1] 李元东[1,2] 马颖[1,2] 陈体军[1,2] 

机构地区：[1]兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室培育基地,兰州730050 [2]兰州理工大大学有色金属合金及加工教育部重点实验室,兰州730050

出　　处：《Transactions of Nonferrous Metals Society of China》2013年第3期567-575,共9页中国有色金属学报（英文版）

基　　金：Project (2007CB613700) supported by the National Basic Research Program of China;Project (50964010) supported by the National Natural Science Foundation of China

摘　　要：A novel rheocasting process, self-inoculation method （SIM）, was developed for the microstructure control of semisolid wrought Mg alloy. This process involves mixing between liquid alloy and particles of solid alloy （self-inoculants）, subsequently pouring the mixed melt into a special designed multi-stream fluid director. The primary phase with dendritic morphology in the conventionally cast AZ31 alloy has readily transformed into near spherical one in the slurry produced by SIM from melt treatment temperature between 690 ℃ and 710 ℃ and self-inoculants addition of 3%-7%. Achievement of the non-dendritic microstructure at the higher melt treatment temperature requires more self-inoculants addition or decreases in the slope angle of fluid director. Primary phase in the slurry thus produced has attained an ideally globular morphology after isothermal holding at 620 ℃ for 30 s. The increasing holding time leads to decrease of shape factor but the coarsening of particle size. The spheroidization and coarsening evolution process of solid particles during the isothermal holding were analyzed by Lifshitz-Slyozov-Wagner （LSW） theory.采用新型自孕育流变铸造技术对变形镁合金半固态组织进行控制。该工艺过程为将合金熔体与一定量的合金固体颗粒（自孕育剂）混合,然后将混合金属通过一个多流股导流器浇入铸型或收集器。结果表明：采用自孕育工艺,合金熔体处理温度690~710℃,孕育剂的加入量为3%~7%时能有效将AZ31镁合金传统铸造中的粗大枝晶组织转变为细小、近球状的非枝晶组织;当合金熔体处理温度较高时,增加孕育剂的加入量或减小导流器的倾斜角度有利于获得非枝晶组织。自孕育工艺制备的AZ31镁合金半固态浆料在620℃等温保温30s后能有效改善初生α-Mg颗粒的圆整度;延长保温时间有助于减小颗粒的圆整度,但同时颗粒发生粗化。利用Lifshitz-Slyozov-Wagner（LSW）理论对初生相颗粒在等温保温过程中的组织圆整、粗化过程进行了分析。

关 键 词：AZ31 alloy MICROSTRUCTURE semisolid rheocasting self-inoculation method 

分 类 号：TG292[金属学及工艺—铸造]