中文摘要：

利用消失模铸造工艺,通过正交实验合金化工艺,重点研究了表面合金化的形成机理,建立了消失模铸件表面合金化模型,分析了合金化过程的动力。在不同真空度、金属粒度、温度为780℃的条件下进行浇注,发现在镁合金基体表面形成均匀的合金化层,通过扫描电镜（SEM）分析表层组织变化,对生成的新相进行微区成分和表层线成分分析。研究表明,在表层生成的新相主要是Mg17Al12,并且表层显微硬度明显高于基体。分析了合金化机理和影响形成均匀合金化层的主要因素,得出了合金化颗粒粒度和铸渗动力在合金化过程中起关键作用,随着合金化颗粒粒度和真空度增大,表面合金化效果明显得到了提高。

英文摘要：

Surface alloying forming mechanism was investigated under lost foam casting （LFC ） technology through orthogonal experiment.Surface alloyed model was established and driving force was analyzed.Homoge-neous alloyed layer has been formed on the Mg-alloy matrix on condition that the vacuum degree and metal grain size were different,pouring temperature was 780 ℃ respectively,scanning electron microscopy （SEM）was used to examined the change of surface layer microstructure,micro area composition analysis of new phase formed on the matrix and line scan composition characteristics on the surface were carried out.The results show that the surface layer consists ofβ- Mg17 Al12 phase,micro-hardness value was enhanced greatly compared with the matrix.Analyzed the alloying mechanism and the important factors during the alloying process that influ-enced the formation of uniform alloyed layer,it has been found that alloying metal grain size and casting infil-tration driving force are the key factors in the experiment,with the increase of grain size and vacuum degree, the surface alloying effect has become better.