(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083；
2. 廣東省材料與加工研究所，廣州 510650；
3. 華南理工大學(xué) 國(guó)家金屬材料近凈成形工程技術(shù)研究中心，廣州，510641；
4. 柳州職業(yè)技術(shù)學(xué)院 機(jī)電工程學(xué)院，柳州 545005)
摘 要: 通過光學(xué)顯微鏡(OM)、掃描電鏡(SEM)、拉伸性能測(cè)試和DSC差熱分析等方法系統(tǒng)研究Al-5Ti-1B、Sr、La、Ce對(duì)A356.1鋁合金組織和性能的影響。結(jié)果表明：Al-5Ti-1B對(duì)A356.1合金中初生α(Al)晶粒的細(xì)化作用十分顯著，而對(duì)共晶硅和富鐵相沒有明顯變質(zhì)作用。Sr能有效地將A356.1合金中粗大、狹長(zhǎng)的板條狀轉(zhuǎn)變?yōu)榧?xì)小的顆粒狀和短纖維狀，從而大幅降低共晶硅的長(zhǎng)度，并顯著改善共晶硅的形狀系數(shù)，但對(duì)初生α(Al)相和富鐵相沒有明顯的細(xì)化變質(zhì)作用。La、Ce對(duì)A356.1合金中初生α(Al)、共晶硅和富鐵相均有一定的細(xì)化變質(zhì)作用，但細(xì)化效果遠(yuǎn)不及Al-5Ti-1B，變質(zhì)效果明顯不如Sr。加入RE元素后，富鐵相的形態(tài)未發(fā)生明顯變化，但長(zhǎng)度大幅減小，說明RE對(duì)富鐵相的長(zhǎng)大具有顯著的抑制作用。當(dāng)采用Sr變質(zhì)時(shí)，合金的綜合力學(xué)性能達(dá)到最佳，其中伸長(zhǎng)率較添加Al-5Ti-1B、La、Ce時(shí)的分別提高56.8%、32.7%和21.1%。
關(guān)鍵字: 變質(zhì)處理；A356鋁合金；微觀組織；力學(xué)性能
（1. School of Materials Science and Engineering, Central South University, Changsha 410083 China;
2. Guangdong Institute of Materials and Processing, Guangzhou 510650, China;
3. National Engineering Research Centre of Near-net-shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510641, China;
4. School of Mechanical and Electrical Engineering, Liuzhou Vocational and Technical College, Liuzhou 545005, China）
Abstract:The effects of Al-5Ti-1B, Sr, La and Ce on structures and properties of A356.1 aluminum alloy were investigated by optical microscopy (OM), scanning electron microscopy(SEM), tensile test and DSC differential thermal analysis systematically. The results show that Al-5Ti-1B has remarkable effect on the refinement of primary α(Al) grains in A356.1 alloy, but it has no obvious modification effect on eutectic silicon and iron-rich phase. Sr can effectively transform the thick and narrow strips into fine grains and short fibers in A356.1 alloy, thus it can greatly reduce the length of eutectic silicon and significantly improve the shape coefficient of eutectic silicon, but it has no obvious refining and modification effect on primary α(Al) phase and iron-rich phase. Both La and Ce can refine and modify the primary α(Al), eutectic silicon and iron-rich phase in A356.1 alloy, but its refinement effect is less than that of Al-5Ti-1B, and its modification effect is obviously less than that of Sr. After adding RE element, the morphology of iron-rich phase does not change substantially, but its length decreases significantly which indicates that RE have a remarkable inhibition on the growth of iron-rich phase. The comprehensive mechanical properties of the alloy that added Sr achieve the best. Compared with the Al-5Ti-1B, La and Ce, the elongation of the A356.1 alloy that modified by Sr is increased by 56.8%, 32.7% and 21.1%, respectively.
Key words: modification; A356 Al alloy; microstructrue; mechanical property
