Y变质SiC_P/AZ61复合材料的半固态等温热处理组织演变  

Microstructure evolution of SiC_P/AZ61 composites modified by 0. 5wt% Y during semi-solid isothermal heat treatment

作　　者：张发云[1] 

机构地区：[1]新余学院新能源科学与工程学院,江西新余338004

出　　处：《金属热处理》2013年第8期42-46,共5页Heat Treatment of Metals

基　　金：国家自然科学基金(50765005)

摘　　要：采用半固态等温热处理法研究了0.5wt%Y变质SiCP/AZ61复合材料的组织演变过程。结果表明,本试验中变质后SiCP/AZ61复合材料最佳半固态组织的制备工艺条件为:加热温度595～600℃、保温30～60 min。与未变质SiCP/AZ61复合材料相比,0.5wt%Y变质SiCP/AZ61复合材料的粗化速率常数较小,具有较好的热稳定性;加热温度高于605℃时,0.5wt%Y变质SiCP/AZ61复合材料中液相体积分数较高,试样出现严重变形和流淌,不能满足后续触变成形时的组织要求。在整个半固态等温热处理过程中,0.5wt%Y变质SiCP/AZ61复合材料组织的演化机制主要体现为:枝晶臂及晶粒间熔合合并→β相熔化晶界分离→晶粒组织(α-Mg)部分球化→完全球化→粗化长大。Microstructure evolution of SiCP/ AZ61 composites modified by 0.5wt% Y during semi-solid isothermal heat treatment was researched.The results indicate that the optimal process parameters for preparing semi-solid microstructure of SiCP/ AZ61 composites modified by 0.5wt% Y were reheating temperature of 600 ℃ and isothermal holding time of 30-60 min.Compared with unmodified SiCP/ AZ61 composites,the coarsening rate constant of SiCP / AZ61 composites modified by 0.5wt% Y is smaller and it possesses high stability.When the heating temperature exceeds 605 ℃,the liquid volume fraction of SiCP/ AZ61 composites modified by 0.5wt% Y increases,the specimen appears serious distortion and liquidity,which does not satisfy the microstructure requirement of the subsequent thixotropic forming.In the semi-solid isothermal heat treatment process,the microstructure evolution law of SiCP/ AZ61 composites modified by 0.5wt% Y is as following： dendrite arm and intergranular coalescence→β phase melted and separation of grain boundary→spheroidization of the grain structure（α-Mg） in part→fully spheroidization→coarsening and growth.

关 键 词：SICP AZ61复合材料 半固态等温热处理法 Y变质 组织演变 

分 类 号：TG331[金属学及工艺—金属压力加工]