(1. 江蘇科技大學(xué) 金屬液態(tài)成形實驗室，蘇州 215600；2. 江蘇科技大學(xué) 材料科學(xué)和工程學(xué)院，鎮(zhèn)江 212003；
3. 大連理工大學(xué) 材料科學(xué)與工程學(xué)院，大連 116024；4. 北京有色金屬研究總院，北京 100088)
摘 要: 利用旋轉(zhuǎn)電磁場攪拌制備AZ91D鎂合金半固態(tài)漿料，在570~600 ℃間不同溫度下澆注金屬型試樣，觀察和分析不同固相率鑄件的微觀組織。結(jié)果表明：較低固相率(fs≤25%)鑄件由α-Mg等軸晶和β-Mg17Al12相組成基體組織，初生固相顆粒以松散的聚團(tuán)形式分散其中；而在相對較高固相率(36%≤fs≤45%)鑄件中，澆注溫度降低，初生相顆粒數(shù)目的劇增和漿料黏度的增大使得初生相顆粒在電磁攪拌形成的黏性剪切作用下相互間發(fā)生摩擦和擠壓塑性變形，從而在高溫條件下焊合形成緊密的團(tuán)簇結(jié)構(gòu)，且聚團(tuán)中初生相顆粒間的晶界表現(xiàn)為低能量的直線型晶界。
關(guān)鍵字: 鎂合金；半固態(tài)；初生相顆粒；電磁攪拌；團(tuán)簇行為
（1. Laboratory of Liquid Metal Forming, Jiangsu University of Science and Technology, Suzhou 215600, China;
2. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
3. School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China;
4. Beijing General Research Institute for Non-ferrous Metals, Beijing 100088, China）
Abstract:AZ91D magnesium alloy semisolid slurry was prepared using rotating electromagnetic stirring, and the molded samples were obtained at different pouring temperatures from 570 ℃ to 600 ℃, then the microstructures were characterized in detail and linked to the corresponding solid volume fraction. The results indicate that the incompact structure agglomerating a few primary solid particles, which disperses in the matrix consisting of α-Mg equiaxed dendrite and network distributed Mg17Al12 precipitates, is observed within structures of low solid fraction (fs) no more than 25%. Meanwhile, for the samples with a higher solid fraction, i.e. 36%≤fs≤45%, due to the reduction in the casting pouring temperature, increasing both the number of primary solid phase and the viscosity of slurry, brings the interaction among the primary particles within vigorously stirring melt, and thus causing slide, friction and plastic deformation between or among the neighboring solid particles. So the primary particles are welded together to form clusters at high temperature and exhibit low energy line-type crystal boundaries.
Key words: magnesium alloy; semisolid; primary solid particles; electromagnetic stirring; agglomerating behavior
