SiC颗粒参与下快冷镁合金异质形核与高温晶粒长大

发布时间：2018-02-21 21:28

  本文关键词： 镁合金 凝固 冷却速率 异质形核 晶粒长大　出处：《中国有色金属学报》2017年02期 　论文类型：期刊论文

【摘要】：采用铜模喷铸与高温退火相结合,研究快冷AZ91+Si C合金组织细化与高温晶粒长大,揭示Si C颗粒对亚快速凝固镁合金异质形核及热稳定性的影响。结果表明:Si C可促进亚快速凝固过程中异质形核,阻碍凝固界面迁移,显著细化喷铸合金组织。400℃等温退火后,组织从枝晶向等轴晶转变并发生明显晶粒长大,快冷AZ91合金保温8 h后平均晶粒尺寸达78μm。添加2%Si C后,晶粒长大得到有效控制,8 h退火处理后平均晶粒尺寸仅为22μm。Si C的存在提高了基体中晶格畸变,退火组织中析出层片状与粒状共存的沉淀相。晶粒细化及Si C的添加提高了快冷镁合金显微硬度。随退火时间延长,合金硬度下降。沉淀相的析出导致AZ91+2%Si C合金硬度增加,最高可达111HV,比AZ91合金的硬度提高63.2%。
[Abstract]:The microstructure refinement and high temperature grain growth of fast cooling AZ91 sic alloy were studied by means of copper mold spray casting and high temperature annealing. The effect of sic particles on the heterogeneous nucleation and thermal stability of subrapid solidified magnesium alloy is revealed. The results show that: sic can promote heterogeneous nucleation during subrapid solidification, hinder the transfer of solidification interface, and refine the microstructure of spray casting alloy after isothermal annealing at .400 鈩，

本文编号：1522906