(燕山大學(xué) 材料科學(xué)與工程學(xué)院 亞穩(wěn)材料制備技術(shù)與科學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室，秦皇島 066004)
摘 要: 在5 K/mm溫度梯度下，在不同的下拉速率(1~50 mm/min)下對(duì)成分為Al-1.0%Ni-3.0%Y(摩爾分?jǐn)?shù))三元共晶合金進(jìn)行下拉定向凝固。通過光學(xué)顯微鏡(OM)、掃描電子顯微鏡(SEM)觀察橫縱截面的組織，研究定向凝固后合金組織的變化規(guī)律；應(yīng)用MIAPS軟件和定量金相法定量分析合金組織中各組成相及共晶團(tuán)的尺寸、體積分?jǐn)?shù)以及共晶層片間距等形貌特征參數(shù)隨凝固條件(v)的變化。結(jié)果表明：定向凝固后，合金組織定向生長(zhǎng)特征明顯；隨著下拉速率的增加，Al-Ni-Y三元共晶合金組織由1 mm/min時(shí)的α(Al)+Al3Y+Al23Ni6Y4三相共晶組織逐漸轉(zhuǎn)變?yōu)橄吕俾? mm/min以上時(shí)的α(Al)+Al3Y相組成的菊花狀共晶和α(Al)+Al23Ni6Y4相組成規(guī)則層片狀共晶所組成的兩個(gè)兩相共晶組織；當(dāng)下拉速率增加到50 mm/min時(shí)，完整的菊花狀共晶組織特征消失，組織破碎細(xì)化，轉(zhuǎn)變?yōu)棣?Al)+Al3Y相枝晶狀共晶。同時(shí)，組織的各特征參數(shù)與下拉速率之間具有明確的數(shù)學(xué)關(guān)系。
關(guān)鍵字: Al-Ni-Y合金；定向凝固；顯微組織；定量分析；三元共晶
（State Key Laboratory of Metastable Materials Science and Technology,
School of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004, China）
Abstract:In order to research the microstructure variation of the Al-Ni-Y ternary alloy with puling-down rates and observe the structure by the optical microscopy (OM) and scanning electronic microscopy (SEM), the upward directional solidification of the alloy with chemical composition of Al-1.0%Ni-3.0%Y (mole fraction) was carried out at the constant temperature gradient of 5 K/mm and different pulling-down rates (1-50 mm/min). The characteristic parameters of the alloy structure, such as the volume fractions and size of each phase and eutectic structure, and the eutectic lamellar spacing were analyzed quantitatively by quantitative metallography and MIAPS software. The results show that the microstructure of the alloy behaves obvious characteristics of directional growth after it is directionally solidified. With the increase of pulling-down rates, the gradual transformation of the microstructure of Al-Ni-Y ternary eutectic alloy transforms from α(Al)+Al3Y+Al23Ni6Y4 ternary eutectic at the pulling-down rate of 1 mm/min to two eutectics consisted of the α(Al)+Al3Y phase irregular chrysanthemum-like eutectic and α(Al)+Al23Ni6Y4 regular lamellar eutectic at the pulling down rate of more than 5 mm/min. When the pulling-down rate increases to 50 mm/min, the complete chrysanthemum- like eutectic structure gradually crushes and transforms into α(Al) and Al3Y phase dendritic eutectic. The mathematical relationships among the characteristic parameters and pulling down rates are unambiguous.
Key words: Al-Ni-Y alloy; directional solidification; microstructure; quantitative analysis; ternary eutectics
