( 1. 中南大學(xué) 材料科學(xué)與工程學(xué)院， 長沙 410083;
2. 電氣通信大學(xué) 機(jī)械工程系, 東京 182-8585， 日本)
摘 要: 采用銅/鋼爆炸復(fù)合板浸鋁鑄造的方法制取了鋁/鋼鑄件。 用掃描電子顯微鏡對復(fù)合鑄件中鋁/鋼界面裂紋的形成以及這些裂紋在不同熱處理制度下和拉剪測試時(shí)的擴(kuò)展形為進(jìn)行了分析。研究表明， 浸鋁鑄造后的裂紋主要存在于波側(cè)面的Fe2Al5層中，且大部分平行于波形界面。 當(dāng)試樣經(jīng)過300~600℃， 30min退火空冷后， 裂紋從波側(cè)面擴(kuò)展到波谷和波峰，同時(shí)在波形界面的塊狀FeAl3相中也出現(xiàn)平行于波形界面的裂紋。鋁和鋼的熱膨脹系數(shù)有較大差異， 而在界面導(dǎo)致殘余熱應(yīng)力是造成界面裂紋產(chǎn)生和擴(kuò)展的主要原因。 由于鋁、 鋼接觸反應(yīng)時(shí)的Kirkendall效應(yīng)使Fe2Al5層中產(chǎn)生較多的微孔，同時(shí)也由于該中間層較厚， 因此微裂紋往往在該層中產(chǎn)生和擴(kuò)展。 拉剪測試后的斷口分析表明材料主要沿鋁/鋼波形界面失效。
關(guān)鍵字: 爆炸焊接； 中間相； Kirkendall 效應(yīng)； 固/液反應(yīng)
castings produced by molten aluminum
and explosively welded Cu/steel plate
YANG Xu-yue2, ZHOU Zhuo-ping1
（ 1. School of Materials Science and Engineering,
Central South University,Changsha 410083, China;
2. Mechanical Engineering Department,
University of Electro-communications,Tokyo 182-8585, Japan）
Abstract: Al/steel bonding castings was manufactured by the molten aluminum and explosively welded Cu/steel plate. Crack initiation and propagation at Al/steel interface were investigated by SEM in the as-cast condition as well as in specimens which were heated at various temperatures and then air-cooled. The main cracks are found in the Fe2Al5 continuous intermetallic layer at the ridges of the wavy Al/steel interface and most of these cracks are parallel to the wavy interface. Being heated at different temperatures from 300℃ to 600℃, and then air-cooled, these cracks propagate from ridges to the vales and peaks, and also appear in FeAl3 blocks as well. Most of these cracks are found to be parallel to the wavy interface too. The residual stress due to different thermal expansion coefficients of the interacting phases and the volume change effect associated with the formation of intermetallic compounds, is suggested to be responsible for the crack initiation. Kirkendall effects during the formation of Fe2Al5 result in amounts of tiny holes in this layer, which might facilitate the crack initiation and propagation afterwards.
Key words: explosive welding; intermetallics; Kirkendall effects; solid-liquid interaction
