( 1. 西北工業(yè)大學(xué) 應(yīng)用物理系, 西安 710072;
2. 西北工業(yè)大學(xué) 凝固技術(shù)國(guó)家重點(diǎn)實(shí)驗(yàn)室， 西安 710072)
摘 要: 利用等溫液淬的方法， 研究了Al-18%Si過共晶合金熔體中初生硅的生長(zhǎng)行為及機(jī)制。結(jié)果表明： 重熔過程中熔體中未溶解的硅相粒子， 在凝固過程中可成為初生硅生長(zhǎng)核心， 并且未熔顆粒與初生硅形狀之間存在明顯對(duì)應(yīng)關(guān)系； 初生硅的生長(zhǎng)機(jī)制不是惟一的，既可以以孿晶凹角（TPRE）機(jī)制生長(zhǎng)，還可以以層狀機(jī)制生長(zhǎng)， 初生硅最終形狀還要取決于溶質(zhì)傳輸?shù)葎?dòng)力學(xué)環(huán)境； 隨著熔體過熱溫度的升高， 凝固組織中初生硅形狀由多邊形向星形及樹枝狀轉(zhuǎn)變。
關(guān)鍵字: 初生硅; 晶體生長(zhǎng); 鋁硅合金
（ 1. Department of Applied Physics, Northwestern Polytechnical University, Xi′an 710072, China;
2. State Key Laboratory of Solidification Processing,
Northwestern Polytechnical University, Xi′an 710072, China）
Abstract: The process and mechanism of primary silicon growth in the Al-Si hypereutectic melt were studied by quench interrupting. The results show that the undissolved silicon particles in the melt become the cores of primary silicon precipitated in solidification and there is a close relationship between the shape of primary silicon and undissolved silicon particles. The growth of silicon follows not only the twin plane re-entrant edge(TPRE) mechanism, but also layer mechanism as well. Meanwhile, the shape of primary silicon also relies on kinetic surroundings, such as the transmitting of solute. At higher overheating temperature, the shape of primary silicon becomes the star-shape and tree-shape.
Key words: primary silicon; crystal growth; Al-Si alloy
