(北京工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院， 北京 100022)
摘 要: 采用鋼模鑄造法制備了不同含量的稀土元素鉺的Al-6Zn-2Mg合金， 利用金相組織觀察、掃描電鏡、 透射電鏡與能譜分析等分析測(cè)試手段， 研究了鉺在合金中的存在形式與細(xì)化機(jī)理。 結(jié)果表明： 鉺在合金中主要有3種存在形式， 即固溶到基體α(Al)中、 形成初生Al3Er相或以共晶化合物的形式分布在晶界、 以細(xì)小Al3Er形式在晶內(nèi)析出；不同含量的鉺能不同程度地細(xì)化晶粒， 當(dāng)鉺含量不超過0.25%時(shí)，枝晶間距減少， 但晶粒沒有明顯細(xì)化， 當(dāng)鉺含量達(dá)0.4％時(shí)，細(xì)化效果已非常顯著， 隨著鉺含量的增大， 晶粒略為細(xì)小； 不同含量的鉺對(duì)合金的細(xì)化機(jī)理取決于它在合金中的存在形式， 當(dāng)鉺含量較低時(shí)， 其細(xì)化機(jī)理符合傳統(tǒng)的稀土鋁合金細(xì)化機(jī)理，當(dāng)鉺含量較高時(shí)， 由于在熔體中形成了初生Al3Er相，這些Al3Er相可以作為非均質(zhì)核心而使晶粒得到細(xì)化，是合金的主要細(xì)化機(jī)理。
關(guān)鍵字: 鉺; Al-Zn-Mg合金; Al3Er
element Er in Al-Zn-Mg alloy
RUAN Hai-qiong, ZUO Tie-yong
（College of Materials Science and Engineering,
Beijing University of Technology, Beijing 100022, China）
Abstract: Al-6Zn-2Mg alloys containing different contents of Er were prepared by steel mould casting. The form of Er in Al-6Zn-2Mg alloy and its refinement mechanism were studied with OM, SEM, TEM and EDS. The results show that Er exists in three forms: resolved in α(Al) based solid solution, forming primary phase Al3Er or eutectic compound in grain boundary, precipitated in the form of the fine Al3Er particles. The addition of Er can be capable of refining grain to a certain degree: the dendritical arm space of the alloy containing less than 0.25% Er becomes small, however the grain seldom keeps the same size. The effect of grain refinement becomes remarkably great when containing up to 0.4% Er. The grain becomes rather fine when the content of Er is more than 0.4%. The refinement mechanism of Er addition depends on the content of Er. The refinement mechanism of the alloy containing less Er conforms to the traditional theory for rare-earth aluminum alloy. The grain of the alloy containing more Er is refined because of the formation of primary Al3Er, and the primary Al3Er can act as heterogeneous nucleus.
Key words: Er; Al-Zn-Mg alloy; Al3Er
