(北京科技大學(xué) 材料科學(xué)與工程學(xué)院，北京 100083)
摘 要: 采用自主研發(fā)的強制對流攪拌裝置(FCR)，研究筒體溫度、澆注溫度和攪拌速度對A356鋁合金半固態(tài)組織的影響規(guī)律，探討半固態(tài)漿料制備過程中的凝固行為。結(jié)果表明：適當(dāng)降低澆注溫度、筒體溫度和提高攪拌速度均有利于半固態(tài)漿料組織的改善，能夠制備晶粒細小、圓整、分布均勻的半固態(tài)組織；當(dāng)澆注溫度為620~630 ℃、筒體溫度為570~580 ℃、筒體轉(zhuǎn)速為200 r/min以上時，均能獲得理想的半固態(tài)漿料，其初生固相顆粒平均直徑在80 μm以下，形狀因子在0.75以上；強制對流攪拌裝置極大地改變了傳統(tǒng)凝固條件下熔體依靠傳導(dǎo)單向傳熱和擴散緩慢傳質(zhì)的狀態(tài)，使熔體的溫度場和成分場趨于一致，破壞了枝晶生長的條件，有利于獲得較好的半固態(tài)組織。
關(guān)鍵字: A356鋁合金；半固態(tài)；強制對流；流變成形；組織演變
（School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing100083, China）
Abstract:A356 aluminum alloy semisolid slurry was prepared by self-developed forced convection rheoforming machine (FCR). The effects of barrel temperature, pouring temperature and rotation speed on the microstructure of semisolid slurry were investigated. The solidification behavior of the semisolid slurry preparation was discussed. The results show that reducing the barrel temperature and pouring temperature and increasing the rotation speed appropriately are beneficial to obtain semisolid slurry with fine and spherical solid particles distributed in the matrix uniformly. The desirable semisolid slurry with average primary solid phase diameter of below 80μm and shape factor of above 0.75 can be obtained at pouring temperature of 620-630 ℃, barrel temperature of 570-580 ℃ and rotation speed over 200 r/min. The FCR device can greatly change the situation that the melt relies on diffusion to transfer the heat and mass in traditional solidification conditions. It destroys the generation environment of dendrites. The temperature field and the composition of the melt are going uniformly, which will be advantage to obtain better semisolid microstructure.
Key words: A356 aluminum alloy; semi-solid; force convection; rheoforming; microstructure evolution
