( 1. 哈爾濱工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院， 哈爾濱 150001;
2. 西北工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院， 西安 710072)
摘 要: 考察了包晶合金分別在定向凝固初始過渡及穩(wěn)態(tài)生長(zhǎng)階段的凝固特性; 分析了凝固過程中液-固界面前沿兩相形核過冷與成分過冷的條件及溫度梯度(G)和生長(zhǎng)速度(v)對(duì)兩相競(jìng)爭(zhēng)生長(zhǎng)的影響和帶狀結(jié)構(gòu)形成與共生生長(zhǎng)的條件, 確定了出現(xiàn)帶狀結(jié)構(gòu)所必需的成分和G/v條件。 計(jì)算了TiAl合金在初始過渡階段初生相及包晶相的競(jìng)爭(zhēng)生長(zhǎng)和向穩(wěn)態(tài)發(fā)展的過渡機(jī)制, 并應(yīng)用界面響應(yīng)函數(shù)建立了不同成分TiAl合金在穩(wěn)態(tài)生長(zhǎng)過程中相與組織隨生長(zhǎng)速度演化的競(jìng)爭(zhēng)選擇模型及相應(yīng)的凝固組織圖, 預(yù)測(cè)了TiAl合金在不同凝固條件下可能形成的相與組織形態(tài)。在所選的合金成分范圍內(nèi)定向?qū)嶒?yàn)所得的凝固組織與計(jì)算預(yù)測(cè)的組織選擇圖有較好的一致性。
關(guān)鍵字: TiAl包晶合金; 定向凝固; 組織選擇
LI Shuang-ming2, GUO Jing-jie1
（ 1. School of Materials Science and Engineering,
Harbin Institute of Technology, Harbin 150001, China;
2. School of Materials Science and Engineering,
Northwestern Polytechnical University, Xian 710072, China）
Abstract: The examination on solidification characteristics of Ti-Al peritectic alloys was dealt with in both initial transient and steady state separately, the nucleation and constitutional supercooling of both phases at the solid/liquid interface and the effect of thermal gradient and growth velocity on the competitive growth of two phases were analyzed, and the condition of band structure formation and coupled growth was also determined. The composition range and G/v ratio to form the band structures were determined. The competitive growth between primary and peritectic phases was investigated during the initial transient and their development to steady-state growth for TiAl alloy, and the interface response functions were used to determine the selection map of phases and microstructures at different compositions and growth rates during the steady-state growth. The microstructures from directionally solidified TiAl alloys with given compositions were in good agreement with the predicted selection map.
Key words: TiAl peritectic alloy; directional solidification; microstructure selection
