摘要与其他合金相比，镁合金具有密度小，比强度以及比刚度高等优良性能，是目前研究最热门的材料之一。但是镁合金易氧化，在熔炼的过程中易形成氧化夹渣、气孔等缺陷。工业上镁合金熔炼制备工艺逐渐发展成熟，然而在实际科研工作中，在简陋的实验室条件下由于受实验设备等的限制，其熔炼制备工艺有别于成熟工业常采用的工艺。87190

本文基于实验室简陋的条件下对镁合金熔炼设备进行简单改造，并且对其工艺重新设计。文章从熔炼炉、熔炼坩埚以及浇注模具等方面来改造镁合金熔炼设备：选择实验室常见井式电阻炉进行熔炼；用挡渣配合坩埚进行除渣；选用TL—4号涂料对浇注模具进行喷涂。从熔炼、精炼以及浇注等方面来重新设计其在实验室的制备工艺：选择SF6和CO2为阻燃气体进行保护熔炼且设定配比分数为SF6：CO2 =1:40；熔炼过程中温度达到730℃时加入Mg-Zr中间合金进行合金化，对熔液搅拌3~5min并保温静置15~30min；精炼过程选用RJ-2精炼剂，加入后对熔液搅拌5~8min并升温至760℃保温静置约25min；浇注前先向模具内通入保护气体2~3min，在720℃时进行浇注。

最后，对按照此工艺制备出的铸锭进行组织与缺陷的观察和分析，对设计出的工艺进行评定，为进一步优化工艺奠定基础。

毕业论文关键词：镁合金；熔炼；精炼；组织；缺陷

Abstract Compared with other alloys, magnesium alloy has excellent performance such as low density, specific strength and high stiffness ratio and is one of the most popular material in the present study。However，the magnesium alloy is easy to be oxidized, and the slag, porosity and other defects are easy to be formed in the process of melting。 Magnesium alloy melting preparation technology of industry has gradually matured。 However, in practical research work，when smelting a small amount of experimental magnesium alloy material in simple laboratory conditions, the melting preparation technology is often different from mature industry due to the limitation of the equipment。 

In this paper, a modification of the magnesium alloy melting equipment is carried out and the melting process is redesigned based on the simple laboratory conditions。 The magnesium alloy smelting equipment are reformed from the aspects of smelting furnace, smelting crucible and casting mould:Choosing common well type resistance furnace in laboratory for melting ;Using slag board with crucible for deslagging；Selecting the TL - 4 paint to spray casting mould。

The preparation process was reformed from the aspects of melting, refining, casting and so on:Choosing SF6 and CO2 as the flame retardant for gas protected melting and seting the ratio of fraction with SF6: CO2 = 1:40;Alloying with Mg-Zr intermediate alloy in s melting process when the temperature reaches the 730℃，stirring for 3 to 5 minutes and sitting for 15 to 30minutes;Selecting RJ-2 refining agent in the refining process,stirring for 5~8 minutes,sitting for about 25 minutes and heating to 760℃。。 Passeing the protective gas into the mold prior for 2 to 3 minutes to casting and the casting is carried out at 720℃。

Finally,observe and analyze the microstructure and defect of the cast ingot and assess the process to lay the foundation for further optimization。

Keywords: magnesium alloy; melting; refining; microstructure; defect

目  录

第一章  绪论 1

1。1 本课题研究的意义和目的 1

1。2 镁合金的应用 2

1。3 镁合金熔炼保护技术的研究现状以及存在的问题 3

1。3。1 熔剂保护法