消失模铸造镁合金表面合金化工艺因素的研究  

Surface Alloying Process Factors of Lost Foam Casting Magnesium Alloy

作　　者：张雄[1] 董选普[1] 霍国君[1] 陈东风[1] 

机构地区：[1]华中科技大学材料成形与模具技术国家重点实验室,湖北武汉430074

出　　处：《铸造》2009年第8期780-783,共4页Foundry

基　　金：国家自然科学基金项目(50775085)

摘　　要：研究了Al粉粒度及真空度对AZ91D镁合金消失模铸造表面合金化过程的影响。研究结果表明，真空度为0．06MPa，Al粉粒度为75μm时，表面合金化效果较好，合金化元素Al主要以第二相的形式均匀分布在合金化层中，合金化层深度达到300μm。同时，对真空度影响表面合金化的机制做了初步探索，发现抽真空形成的负压能增加镁合金液的渗流动力，而且真空度存在一个处于0．02～0．04MPa的临界值。真空度过小，EPS泡沫裂解产物将无法完全排出合金涂料层，导致表面合金化层会出现夹层现象；真空度过高则会引起各金化层产生孔洞，使得合金化表层性能不均匀。The effect of AI powder particle size and vacuum degree in the surface alloying process of lost foam casting AZ91D magnesium alloy was studied. The results show that the surface alloying effect was the best when the vacuum degree was 0.06 MPa and the particle size of AI powder was 75 μm. Alloying elements AI evenly distributed in the alloying layer mainly in the form of the second phase, and the depth of the surface alloying layer reached to 300 μm. At the same time, the mechanism of the effect of vacuum degree on surface alloying was preliminarily explored. It was found that the negative pressure formed in the vacuum pumping process could increase the seepage dynamic of magnesium alloy fluid, and there was a critical vacuum degree between 0.02-0.04 MPa. If the vacuum degree was too low, the pyrolysis products of EPS could not be completely discharged from the alloying coating layer, resulting in interlayer phenomenon in the surface alloying layer. But if the vacuum degree was too high, porosities would appear in the alloying layer, making the performance of surface alloying layer non-uniform.

关 键 词：表面合金化 镁合金 消失模铸造 

分 类 号：TG174.4[金属学及工艺—金属表面处理]