摘要
探讨了Al-5Ti-1B-0.5RE中间合金对A356铝合金的细化效果,并用OM、SEM、EDAX等进行微观组织观察分析。结果表明,该中间合金对A356铝合金不仅具有明显的晶粒细化效果,且具有显著的细化枝晶作用;RE对该中间合金的细化效果起到了重要作用,即该中间合金中(AlTiRE)相在铝液中不稳定,很快分解释放出RE元素,降低了表面能,减少了TiB2相的聚集倾向,增加了形核粒子的数量;同时RE易吸附偏聚在铝熔体的晶界和相界面上,阻碍TiAl3相的生长,阻止针条状TiAl3相的形成,也增加了形核几率。此外,RE的加入可有效保证该细化剂及铝熔体的冶金质量,在一定程度上也增强了该细化剂的细化效果。
Microstructure of A356 aluminum alloy refined by Al5Ti1B0.5RE master alloy was observed by OM (optical microscope), SEM (scanning electronic microscope) and EDAX to understand the refining effects of the master alloy. The results indicate that the master alloy can greatly refine the grain size and dendrite in A356 aluminum alloy, in which the RE exhibits significantly positive role. AlTiRE phase formed in the master alloy with RE is unstable in Al melt it and could dissolved quickly into Al melt to release RE elements, which can decrease surface energy and tendency of segregation of TiB2 phase, increasing nuclei amounts. Meanwhile, RE can restrain the growth of TiAl3 phase and the formation of acicular TiAl3 phase as a result of RE easily segregating in grain boundary and phase interface of Al melt, raising the nucleation rate. In addition, RE can improve the refining effects of the master alloy due to effectively purifying the metallurgical quality of the master alloy and Al melt.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2008年第10期795-797,共3页
Special Casting & Nonferrous Alloys
基金
福建省教育厅科技资助项目(JA07202)
