( 1. 東北大學(xué) 理學(xué)院， 沈陽(yáng) 110004；
2. 東北大學(xué) 材料電磁過程研究教育部重點(diǎn)實(shí)驗(yàn)室， 沈陽(yáng) 110004)
摘 要: 利用光學(xué)顯微鏡、 X射線衍射儀和透射電鏡， 研究了在不同電流和頻率作用下， 半連鑄d100 mm高強(qiáng)高韌Al合金鑄錠組織結(jié)構(gòu)的變化。 結(jié)果表明： 在電磁場(chǎng)頻率為25 Hz時(shí)， 當(dāng)電流從60 A增大到100 A時(shí)， 電流越大， 晶粒細(xì)化越明顯； 在電流為100 A時(shí)， 晶粒細(xì)化的最佳頻率為25 Hz； 與常規(guī)鑄錠相比， 隨電流增大， 鑄錠內(nèi)沿［311］方向產(chǎn)生的織構(gòu)逐漸消失， 并且鑄錠邊緣和中心部位的點(diǎn)陣常數(shù)逐漸趨于一致， 這表明溶質(zhì)元素的分布更加均勻； 在電流和頻率分別為100 A和25 Hz時(shí)， 晶界附近無析出帶寬度變窄， 約為100 nm。 此時(shí)， 無論是在晶內(nèi)還是沿晶界， 析出相的尺寸明顯減小， 并且有亞穩(wěn)相， 形態(tài)近似為顆粒狀。
關(guān)鍵字: 金屬材料； 組織結(jié)構(gòu)； 低頻電磁場(chǎng)鑄造； 高強(qiáng)Al合金
（ 1. College of Science, Northeastern University,
Shenyang 110004, China;
2. The Key Laboratory of Electromagnetic Processing of
Materials, Ministery of Education, Northeastern University,
Shenyang 110004, China）
Abstract: Microstructures of semi-continuously cast d100 mm Al alloy ingot at different current intensities and frequencies were studied in details by optical microscope, X-ray diffraction and TEM to investigate the effect of electromagnetic field on microstructures of ingot. When current increases from 60 to 100 A at 25 Hz, the grains are gradually refined; When current is 100 A, the optimum frequency of grain refinement is 25 Hz. In contrast to the as-cast ingot, with the increase of current, texture produced along ［311］ direction gradually eliminates, and lattice constants at the center and edge of the ingot are more and more close, which shows that the distribution of solute atoms is more uniform. At current of 100 A and frequency of 25 Hz, width of precipitate-free zones on both sides of grain boundary becomes narrower and is about 100 nm, the size of precipitates deposited both inside grains and along grain boundaries becomes smaller, and there exists metastable phase, with basically granular shapes.
Key words: metallic materials; microstructure; low frequency electromagnetic casting; high-strength Al alloy
