(西安工業(yè)大學(xué) 陜西省光電功能材料與器件重點(diǎn)實(shí)驗(yàn)室，西安 710021)
摘 要: 采用高速攝影儀和掃描電子顯微鏡研究富鈰混合稀土(RE)加入量對(duì)Al-80%Si(質(zhì)量分?jǐn)?shù))合金懸浮試樣凝固行為和凝固組織的影響規(guī)律。結(jié)果表明：Al-80%Si合金中初生硅的生長(zhǎng)特性、晶粒尺寸和分布受過(guò)冷度影響明顯；隨著RE加入量的增加，Al-80%Si合金中初生硅由小平面生長(zhǎng)向中間生長(zhǎng)方式轉(zhuǎn)變所需的臨界過(guò)冷度ΔT1以及由中間生長(zhǎng)向非小平面生長(zhǎng)方式轉(zhuǎn)變所需的臨界過(guò)冷度ΔT2均越來(lái)越低；當(dāng)RE加入量達(dá)到1.5%(質(zhì)量分?jǐn)?shù))時(shí)，ΔT1和ΔT2分別降至最低值78和180 K；繼續(xù)增加RE的加入量，ΔT1和ΔT2不發(fā)生變化。在同一臨界過(guò)冷度ΔT2下，隨RE加入量的增加，初生硅的尺寸從40 μm減小到20 μm。
關(guān)鍵字: Al-80%Si合金；初生硅；過(guò)冷度；富鈰混合稀土
（Shanxi Province Key Laboratory of Photoelectric Functional Materials and Devices,
Xi’an Technological University, Xi’an 710021, China）
Abstract:The effect of the addition level of cerium-rich mischmetal (RE) elements on the solidification behavior and as-solidified microstructure for the Al-80%Si (mass fraction, %) alloy prepared by electromagnetic levitation method was investigated by using high speed camera and scanning electron microscope. The results show the growth behavior, grain size and distribution of primary silicon are obviously dependent on the nucleation undercooling. The critical undercooling ΔT1, for the growth-mode transition from lateral mode to intermediary one, and the critical undercooling ΔT2, for the growth-mode transition from intermediary mode to continuous one, both decrease with increasing the RE addition level. When the RE content is 1.5% (mass fraction, %), the values of ΔT1 and ΔT2 reach the minimum of 78 K and 180 K, respectively. With further increasing the RE content, the critical undercoolings, ΔT1 and ΔT2 then tend to be steady. Under the same critical undercooling ΔT2, the size of primary silicon decreases from 40μm to 20μm with the increase of RE content.
Key words: Al-80%Si alloy; primary silicon; undercooling; cerium-rich mischmetal
