Mg-25La中间合金无熔剂保护熔炼工艺研究  

Preparation of Mg-25La Master Alloy by Non-Flux Melting Process

作　　者：胡文鑫[1] 陈国华[1] 杨正华[1] 

机构地区：[1]包头稀土研究院稀土冶金及功能材料国家工程研究中心,内蒙古包头014030

出　　处：《稀有金属》2014年第1期8-14,共7页Chinese Journal of Rare Metals

基　　金：国家科技部"863计划"项目(2010AA03A407)资助

摘　　要：以镁合金专用熔炼炉为设备，在SR6＋N2保护气氛下对熔炼过程中熔炼温度、物料加入速率、熔炼时间、浇铸温度以及保护气中sFs浓度对合金收率、合金元素La收率、合金元素La偏析程度等制备工艺技术指标的影响进行研究，确定Mg-25La中间合金的高品质制备工艺条件为：熔炼温度685～695℃、物料加入速率为30g·min^-1、熔炼时间90min、浇铸温度680℃以及保护气中sF6浓度为0．1％（体积分数）。基于以上工艺条件所获得合金元素收率大于98％，上部及下部的稀土元素成分比为0．99：1．00，偏析程度为±0．3％-0．6％（质量分数）；组分中稀土元素含量为25．0％±0．5％（质量分数），合金内部无氧化缺陷、气孔，合金组分均一，成分稳定。通过对合金所进行的X射线衍射（XRD），能谱（EDS）及扫描电镜（SEM）分析可知，当镧元素含量为25．0％时，合金中出现连续分布的Mg17La2共晶相，近似网状分布，且尺寸粗大。同时在晶粒内部及晶界之上出现一定数量的、分布不均匀细小第二相颗粒Mg2La相，该相与Mg17La2相同为Mg-25La中间合金的重要强化相。The effect of melting temperature, charging rate of La, melting time, casting temperature and concentration of SF6 in shielding gas on technological index of preparation process, such as yielding rate of alloy, yielding rate of La, segregation of La were studied under SF6 ＋ N2 protection and special magnesium alloy furnace. The results showed that the optimal conditions of preparation of Mg-25 La master alloy were melting temperature of 685 -695 ℃, charging rate of La 30 g.min^- 1, melting time 90 min, casting temperature of 680 ℃and SF6 concentration of 0.1% （volume fraction）. The yield of alloy and yield of La were greater than 98% ; the ratio of La content in the upper part and the under part was 0. 99： 1.00; the segregation degree of La was ±0.3% -0.6% and content of La was 25.0% ± 0.5% （mass fraction）. There were no oxidation defects and stomata in the alloy. The alloy was of homogeneous components and stable composition. The X-ray diffraction （XRD）, energy dispersive spectroscopy （EDS） and scanning electron microsco- py （SEM） analysis results showed that Mg17 La2 eutectic phase presented continuous network distribution with coarse size and a certain amount secondary phase Mg2La presented discontinuous distribution in grain interiors and grain boundary of magnesium alloy with 25. 0% La. Mg17La2 and Mg2La were important strengthening phase for Mg-25La master alloy.

关 键 词：Mg-25La中间合金 无熔剂熔炼 工艺条件 铸锭组织结构 

分 类 号：TG146.22[一般工业技术—材料科学与工程]