摘要
分别采用底注式和顶注式两种浇注系统,得到不同的AZ91-0.45Si镁合金组织,通过分析其铸态显微组织,比较合金中Mg2Si的形貌,探讨浇注方式和冷却速度对Mg2Si相形貌的影响。结果表明,含0.45Si的AZ91镁合金中存在两种形态的Mg2Si相,底注式试样Mg2Si呈不规则多边形,顶注式试样Mg2Si呈"汉字状"。分析认为,Mg2Si相形成的形态与冷却速度相关,冷却速度越快,过冷度和凝固速度就越大;Mg2Si相有足够的时间继续向四周长大,故顶注式试样中的Mg2Si相呈"汉字状"。
Bottom gating system and top gating system were employed to study the effects of pouring mode and cooling rate on casting microstructure of the AZ91-0.45Si alloy by comparing the morphologies of Mg2Si. It was found that the Mg2Si phase in the alloy existed in two different morphologies, the blocky shape in the alloy of the bottom gating system and Chinese characters shape in the top gating system. The formation of Mg2Si was related with the cooling rates, the quiker the cooling rate, the bigger the super-cooling degree and solidification rate. For the alloy of top gating system, the cooling rate is relatively small; the Mg2Si phase had enough time to grow, so the Mg2Si phase in the alloy of top gating system was Chinese characters shape.
出处
《铸造》
CAS
CSCD
北大核心
2009年第9期954-957,共4页
Foundry
基金
广州市应用基础研究项目(2008J1-C271)
