摘要
通过研究Al5Ti1B加入对A356合金凝固过程微观组织演变的影响,探讨Ti/B对A356合金流动性的影响机理。通过研究表明,Al5Ti1B量<0.1%时能够使A356流动性上升,0.1%<Al5Ti1B量<0.5%A356流动性下降。对流动性而言A356最佳Al5Ti1B添加量为0.1%;组织分析认为,少量Al5Ti1B的加入促进α-Al晶粒形核,大量α-Al晶核的形成使周围成分过冷,抑制晶粒迅速长大,相对延长液态时间,使合金流动性提高;继续添加Al5Ti1B,熔体中TiB2异质颗粒过剩,使合金液相线上升,凝固区间扩大,潜热释放不集中,形核温度上升,流动性降低。适量Al5Ti1B的加入能增加A356中α-Al形核率,减小晶粒尺寸,提高流动性。
The effect of Al5Ti1B addition on the solidification microstructure evolution in A356 alloy has been studied, and the fluidity mechanism has also been discussed. The results showed that the fluidity increased when the amount of the addition is less than 0.1%, however, it decreased at the range of 0.1%〈Al5Ti1B〈0.5%. The optimum fluidity can be obtained when the content of Al5Ti1B is equal to 0.1%. Microstructure investigation showed that the nucleation rate of α-Al is increased with small amounts of Al5Ti1B addition, which will lead to super-cooling and restrain the nucleus to grow up, then to prolong liquid time and improve fluidity. Nevertheless, more amounts of Al5Ti1B addition will lead to TiB2 over-much, make the liquid temperature and the area of solidification increase. The fluidity was thus decreased due to the un-uniformity of decalescence and the increasing of nucleation temperature. Appropriate addition of Al5Ti1B will make nucleation rate of α-Al increased and crystal dimension decreased, then improve fluidity consequently.
出处
《铸造》
CAS
CSCD
北大核心
2009年第5期489-493,共5页
Foundry
基金
云南省科技攻关项目资助(2004GG07)
