L1_(2)型Al_(67)Cu_(8)Ti_(25)细化剂的制备及其对铝合金组织的影响

Preparation of L1_(2)-Al_(67)Cu_(8)Ti_(25) Refiner and Effects on Microstructure of Aluminum Alloys

采用单质粉末通过高能球磨和真空烧结制备了L1_(2)型Al_(67)Cu_(8)Ti_(25)金属间化合物,并将其破碎后与Al粉进行混合制备了Al-25Al_(67)Cu_(8)Ti_(25)复合细化剂。研究了球磨时间、烧结温度对制备L1_(2)型Al_(67)Cu_(8)Ti_(25)金属间化合物的影响。以纯铝和Al-5Cu-Mn铸造铝合金为对象,研究了复合细化剂对α-Al宏观和微观组织的影响及作用机制。结果表明,球磨粉末在600℃下烧结可制备单相的L1_(2)型Al_(67)Cu_(8)Ti_(25)化合物颗粒,随着球磨时间增加,烧结形成的化合物颗粒的平均尺寸减小至11μm,形貌趋于球形。Al-25Al_(67)Cu_(8)Ti_(25)复合细化剂对α-Al具有较好的细化效果,加入0.25%的Al_(67)Cu_(8)Ti_(25)细化剂后,纯铝及Al-5Cu-Mn合金的晶粒尺寸分别细化至224μm和137μm。L1_(2)型Al_(67)Cu_(8)Ti_(25)化合物是α-Al的有效形核质点,与α-Al的错配度为2.35%,相比于Al3Ti,其错配度更小,异质形核能力更强。

The L1_(2)-Al_(67)Cu_(8)Ti_(25) intermetallic compound was prepared by high-energy ball milling and vacuum sinter⁃ing,which was crushed and mixed with Al powder to fabricate Al-25Al_(67)Cu_(8)Ti_(25) compound refiner.The influence of milling time and sintering temperature on the preparation of L1_(2)-Al_(67)Cu_(8)Ti_(25) intermetallic compounds were investigated.Taking pure aluminum and Al-5Cu-Mn cast aluminum alloys as objects,effects of compound refiners on the macro⁃structure and microstructure ofα-Al as well as the action mechanism were investigated.The results indicate that the single-phase L1_(2)-Al_(67)Cu_(8)Ti_(25) compound particles are fabribated by sintering the powder at 600℃.With the increase of milling time,the average size of sintered compounds is decreased to 11μm,and the morphology tends to be spherical.Al-25Al_(67)Cu_(8)Ti_(25) compound refiner has a desirable refining effect onα-Al,and the grain size of pure aluminum and Al-5Cu-Mn alloys are refined to 224μm and 137μm,respectively,after adding 0.25%Al_(67)Cu_(8)Ti_(25) compound refiner.L1_(2)-Al_(67)Cu_(8)Ti_(25) compound can act as an effective nucleation ofα-Al with a mismatch degree of 2.35%,which is less than that of Al3Ti,leading to stronger heteronuclear ability.