华华 中中 科科 技技 大大 学学 硕硕 士士 学学 位位 论论 文文 摘摘 要要 镁基金属玻璃具有高的比强度、 优异的耐腐蚀性能， 作为一类轻质高强度材料，具有广阔的应用潜力研究开发具有强玻璃形成能力的新型镁基金属玻璃，特别是在常规 （非真空） 条件下采用工业纯度原材料获得金属玻璃， 具有十分重要的意义而在影响合金玻璃形成能力的因素当中，制备方法和合金成分最为关键，本论文从这两点出发，利用常规（非真空）制备条件和工业纯度原材料对镁基块体非晶合金的制备以及合金的玻璃形成能力进行了研究 考虑到玻璃熔体在熔融状态下粘度大、流动性差、充型困难，本文设计了铜模振动铸造法、中频真空感应炉熔炼制备母合金——熔化浇注成型法、粉体压力制坯——熔化浇注成型法、负压铜模吸铸法等多种制备方法通过多种成分合金对各种实验方法的比较和实验验证，成功开发出负压铜模吸铸制备方法，该方法在高纯氩气保护下熔炼合金，铜模在空气气氛中利用负压吸铸成型，具有操作方便、工艺简单、易于控制的特点配合该制备方法，选用Mg65Cu25Y10成分合金进行对比实验，确定了所开发的新成分合金Mg65Cu25Y10-xNdx（x=0,2,4,6,8,10） 较为合适的工艺参数：在炉温 600℃左右将合金放入炉内加热， 达到 750℃后保温 25 分钟， 随后升温至 800℃搅拌并随即负压吸铸，吸铸温度约 750℃。
制备工艺参数随合金成分变化可在小范围内调整 采用工业纯度的原材料和负压铜模吸铸法制备获得了直径为 3mm的Mg65Cu25Y10-xNdx圆棒试样，分析表明x=0,4,6 成分合金为非晶态，而x=2,8,10 成分合金除含部分非晶外呈较典型的晶体特征 利用光学显微镜(OM)、差示扫描量热分析仪(DSC)、扫描电镜(SEM)、能谱(EDX)和X射线衍射仪(XRD)对试样进行了观察和分析，并首次研究了Nd对Mg-Cu-Y-Nd合金玻璃形成能力的影响 SEM和XRD分析发现x=0 成分合金试样中较为均匀的分布着尺寸大小约 2mµ体积百分含量高达 0.15%的(Cu,Y)非晶氧化物，x=4 成分合金中有 0.18%,但如此高含量的（Cu,Y）非晶氧化物，并未显著影响合金I华华 中中 科科 技技 大大 学学 硕硕 士士 学学 位位 论论 文文 的玻璃形成能力；与x=0 相比，适量Nd替换Y明显提高了合金的玻璃形成能力，当x=4 时合金具有最大的玻璃形成能力，其约化玻璃转变温度为 0.592，过冷液相区宽度高达 66K,DSC分析为单一熔化峰， 且固液两相区(rgTxT∆)lmTT−宽度仅为 16K,表明该成分处于合金系统一个共晶成分点或位于其附近的位置；而x=6 合金玻璃形成能力相比x=0 时略有提高。
初步估算成分为x=4,6 的合金玻璃形成的临界冷却速率cR 约为 100K/s当x=2,8,10 时，由于合金成分明显偏离共晶点，使得固液两相区非常宽（分别为 104K,92K,143K） ，在冷却过程中晶体形核和长大都有较为充分的时间， 利于结晶， 在直径 3mm尺寸最终获得只有少量非晶而主要呈晶体特征的晶体试样，其主要晶体相为Mg(lmTT−)24Y5、Cu5Y、Cu4Nd、Cu2Nd、Mg2Cu等 关键词关键词：镁合金 金属玻璃 负压 铜模 玻璃形成能力 II华华 中中 科科 技技 大大 学学 硕硕 士士 学学 位位 论论 文文 Abstract Mg-based metallic glasses are regarded as a new family of promising materials with high specific strength and excellent corrosion resistance. It makes sense to develop new Mg-based metallic glasses with strong glass forming ability (GFA) especially under the condition of normal equipment (no vacuum) and adopting commercial raw material. Furthermore, the most important factors are preparation method and alloy component in the factors that affect GFA. A lot of research was taken to the preparation technology and GFA of Mg-based metallic glasses based on the two factors. Considering the big viscosity, poor flowability and filling ability of the alloy melt, some preparation methods were developed in this research such as shaking copper mold casting method, smelting master alloy in medium-frequency vacuum induction furnace-- remelting and casting method, powder pressure forming--melting and casting method and copper mold drawing casting method under suction pressure. Compared with each other by experiments, copper mold drawing casting method is the most successful. This method, which adopts the processing of melting in high purity argon shield and drawing-casting under suction pressure in air, has characteristics of easy operation, simple processing and controlling. At the same time, Mg65Cu25Y10 metallic glass was made in experiment for comparison to determine the appropriate processing parameter of new component Mg65Cu25Y10-xNdx（x=0,2,4,6,8,10）. The newly developed process is as following: the crucible with raw material is brought into electric resistant furnace at 600℃,then holding for 25 minutes after reached 750℃, subsequently the melts is stirred at 800℃ and castes at about 750℃.The preparation processing parameters could be adjusted in small scale according to the varying of alloy compositions. A series of samples with diameter 3 mm were made by copper mold drawing-casting method with commercial raw material. The results show that the alloys with compositions III华华 中中 科科 技技 大大 学学 硕硕 士士 学学 位位 论论 文文 of x=0,4,6 are amorphous and the alloys with compositions of x=2,8,10 are typical crystallines, with some non-crystal microstructure among them. The samples were observed and analyzed by means of optical microscope (OM), differential scanning calorimetry (DSC), scan electron microscopy (SEM), energy spectrometer (EDX) and X-ray diffractometry (XRD). And the influence of Nd element on the GFA of Mg-Cu-Y-Nd multicomponent alloy systems was studied for the first time. The results of SEM and XRD analyzing show that: (Cu, Y) amorphous oxide, which reaches 0.15% in x=0 component alloy and 0.18% in x=4 component alloy at volume content, adequately distributes at the size of 2mµ. However, the oxide with so high content didn’t affect the GFA of the alloys obviously. Compared with the alloy of x=0,the GFA of the alloy is improved obviously by appropriate addition of Nd. The best GFA with the 0.592 and rgTxT∆ 66K appears at x=4. Furthermore, the result of DSC analysis shows that there is a single melting peak and the ()lmTT− is a narrow range of 16K at x=4 and it could be included that x =4 is at or near one of the eutectic points in the phase diagram of Mg-Cu-Y-Nd. The GFA of the alloy of x=6 is improved at a certain extent compared to x=0 and the critical cooling rate of glass forming of the alloy at x=4,6 is 100K/s by estimation. But when x=2,8,10 the component of the alloys deviates from the eutectic points and the results is a wide rang of ()lmTT− (104K, 92K, 143K respectively). Therefore the nu。