(1. 南昌大學(xué) 機(jī)電工程學(xué)院，南昌 330031；2. 西北工業(yè)大學(xué) 理學(xué)院，西安 710072；
3. 西北工業(yè)大學(xué) 凝固技術(shù)國家重點實驗室，西安 710072)
摘 要: 針對Pb-Bi包晶合金中高速及低速定向凝固，利用最高界面生長溫度判據(jù)以及充分形核和成分過冷準(zhǔn)則，對Pb-Bi包晶合金定向凝固中初生α和包晶β兩相的相互競爭規(guī)律進(jìn)行預(yù)測。計算結(jié)果表明：在中高速凝固段，與Pb-26%Bi、Pb-28%Bi、Pb-30%Bi和Pb-34%Bi(質(zhì)量分?jǐn)?shù))合金對應(yīng)的α→β轉(zhuǎn)變的臨界生長速度分別為20、14、8.5和2 mm/s；在低速凝固段，合金的相選擇圖分為8個生長區(qū)，其中包括兩相分別以單相生長區(qū)及兩相混合生長區(qū)。利用該相選擇圖，結(jié)合溫度梯度與凝固速度比值(G/V)及合金原始成分(C0)可預(yù)測相選擇規(guī)律及組織形態(tài)。
關(guān)鍵字: Pb-Bi合金；包晶合金；定向凝固；相選擇
（1. School of Mechanical-Electrical Engineering, Nanchang University, Nanchang 330031, China;
2. School of Science, Northwestern Polytechnical University, Xi’an 710072, China;
3. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract:Based on the directional solidification of Pb-Bi peritectic alloys with moderate or high and low growth velocities, the competition between the primary α and peritectic β phases was predicted by using the highest interface growth temperature criterion and the nucleation and constitutional undercooling criterion, respectively. The calculated results show that the critical growth velocities for α→β transition under moderate/high growth velocities are 20, 14, 8.5 and 2 mm/s for Pb-26%Bi, Pb-28%Bi, Pb-30%Bi and Pb-34%Bi (mass fraction) alloys, respectively. For the low growth velocities, the phase selection map is divided into 8 growth zones including the single phase growth zone and the growth zone of two phases mixed. The phase selection and microstructure morphology can be predicted by using the phase selection map combined with solidification rate ratio (G/V) and initial content of the alloy (C0).
Key words: Pb-Bi alloy; peritectic alloy; directional solidification; phase selection
